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Effect of tart cherry juice (Prunus cerasus) on melatonin levels and enhanced sleep quality


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Background: Tart Montmorency cherries have been reported to contain high levels of phytochemicals including melatonin, a molecule critical in regulating the sleep-wake cycle in humans. Purpose: The aim of our investigation was to ascertain whether ingestion of a tart cherry juice concentrate would increase the urinary melatonin levels in healthy adults and improve sleep quality. Methods: In a randomised, double-blind, placebo-controlled, crossover design, 20 volunteers consumed either a placebo or tart cherry juice concentrate for 7 days. Measures of sleep quality recorded by actigraphy and subjective sleep questionnaires were completed. Sequential urine samples over 48 h were collected and urinary 6-sulfatoxymelatonin (major metabolite of melatonin) determined; cosinor analysis was used to determine melatonin circadian rhythm (mesor, acrophase and amplitude). In addition, total urinary melatonin content was determined over the sampled period. Trial differences were determined using a repeated measures ANOVA. Results: Total melatonin content was significantly elevated (P < 0.05) in the cherry juice group, whilst no differences were shown between baseline and placebo trials. There were significant increases in time in bed, total sleep time and sleep efficiency total (P < 0.05) with cherry juice supplementation. Although there was no difference in timing of the melatonin circardian rhythm, there was a trend to a higher mesor and amplitude. Conclusions: These data suggest that consumption of a tart cherry juice concentrate provides an increase in exogenous melatonin that is beneficial in improving sleep duration and quality in healthy men and women and might be of benefit in managing disturbed sleep.
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Effect of tart cherry juice (Prunus cerasus) on melatonin levels
and enhanced sleep quality
Glyn Howatson
Phillip G. Bell
Jamie Tallent
Benita Middleton
Malachy P. McHugh
Jason Ellis
Received: 7 July 2011 / Accepted: 10 October 2011
Ó Springer-Verlag 2011
Background Tart Montmorency cherries have been
reported to contain high levels of phytochemicals including
melatonin, a molecule critical in regulating the sleep-wake
cycle in humans.
Purpose The aim of our investigation was to ascertain
whether ingestion of a tart cherry juice concentrate would
increase the urinary melatonin levels in healthy adults and
improve sleep quality.
Methods In a randomised, double-blind, placebo-con-
trolled, crossover design, 20 volunteers consumed either a
placebo or tart cherry juice concentrate for 7 days. Measures
of sleep quality recorded by actigraphy and subjective sleep
questionnaires were completed. Sequential urine samples
over 48 h were collected and urinary 6-sulfatoxymelatonin
(major metabolite of melatonin) determined; cosinor anal-
ysis was used to determine melatonin circadian rhythm
(mesor, acrophase and amplitude). In addition, total urinary
melatonin content was determined over the sampled period.
Trial differences were determined using a repeated measures
Results Total melatonin content was significantly ele-
vated (P \ 0.05) in the cherry juice group, whilst no dif-
ferences were shown between baseline and placebo trials.
There were significant increases in time in bed, total sleep
time and sleep efficiency total (P \ 0.05) with cherry juice
supplementation. Although there was no difference in
timing of the melatonin circardian rhythm, there was a
trend to a higher mesor and amplitude.
Conclusions These data suggest that consumption of a
tart cherry juice concentrate provides an increase in
exogenous melatonin that is beneficial in improving sleep
duration and quality in healthy men and women and might
be of benefit in managing disturbed sleep.
Keywords Tart cherries Melatonin Sleep Recovery
Tart Montmorency cherries (Prunus cerasus), rich in
numerous phytochemicals, provide a range of health benefits
that include reduction in symptoms associated with gout [1],
down-regulation of circulating inflammatory markers [2],
analgesic effects following long-distance running [3],
reduced oxidative stress [4], improved recovery following
damaging exercise [57] and recently, improved sleep
quality in late-life insomnia [8]. Mechanistically, it is
thought the phenolic compounds within tart cherries act as
‘free radical’ scavengers that reduce oxidative stress [2]. In
addition, the anti-inflammatory properties [9] of tart cherries
have been reported to be at a level comparable to a number of
non-steroidal anti-inflammatory drugs [10]. In particular, the
anthocyanin content of tart cherries, which compares
G. Howatson (&) P. G. Bell J. Tallent J. Ellis
School of Life Sciences, Northumbria University,
Northumberland Building, Newcastle upon Tyne NE1 8ST, UK
G. Howatson
Centre for Aquatic Research, Department of Zoology,
University of Johannesburg, Johannesburg, South Africa
B. Middleton
Centre for Chronobiology, Faculty of Health and Medical
Sciences, University of Surrey, Guildford, UK
M. P. McHugh
Nicholas Institute of Sports Medicine and Athletic Trauma,
Lenox Hill Hospital, New York, NY, USA
Eur J Nutr
DOI 10.1007/s00394-011-0263-7
favourably with other fruits such as sweet cherries [11],
seems to be of most interest, and these are likely to be
responsible for the anti-oxidative and anti-inflammatory
A number of recent studies have shown that consump-
tion of tart cherry juice can accelerate recovery following
strenuous exercise [57], where temporary perturbations in
inflammation and oxidative stress can occur. These
recovery effects have been attributed to the actions of the
antioxidant and anti-inflammatory phytochemicals con-
tained in tart cherries. Pigeon et al. [8] anecdotally reported
claims of improved sleep with cherry juice supplementa-
tion in participants from a previous trial [6]. Interestingly,
in addition to the aforementioned phenolic compounds, tart
cherries contain high concentrations of melatonin [12].
Melatonin has a strong influence on the sleep-wake cycle in
humans and is associated with sleep-promoting properties
[13]. Physiologically, endogenous melatonin secretion
adjusts according to the light/dark cycle and can directly
influence nocturnal core temperature and hence facilitate
the propensity for sleep [14]. Additionally, a strong posi-
tive relationship between increased melatonin and total
sleep time in healthy, young individuals has been previ-
ously demonstrated [15]. Interestingly, the balance of evi-
dence would suggest that exogenous melatonin in the
treatment of insomnia is equivocal at best; however, there
is a good body of support for melatonin use in managing
circadian rhythm disturbance, such as those seen from
travelling time zones [16].
In a recent study, the efficacy of tart cherry juice con-
sumption on sleep indices in a population with late-life
insomnia was examined [8]. They reported modest
improvements in subjective quality of sleep; however, no
objective measures of sleep, such as actigraphy, were
taken, and the potential mechanisms responsible for the
reported sleep improvements (e.g. melatonin) were
impossible to discern. The authors [8] speculated that
increased dietary melatonin associated with consumption
of tart cherry juice might be responsible for the changes.
However, there is an alternative hypothesis; the anti-
inflammatory properties of tart cherries may have some
influence on the pro-inflammatory cytokines involved in
sleep regulation [17]. Given the potential benefits of tart
cherry juice in delivering exogenous melatonin and
improving sleep quality, we hypothesised that the con-
sumption of a tart cherry juice concentrate in young,
healthy adults would increase urinary 6-sulfatoxymelatonin
and improve indices of sleep quality. Therefore, the aim
of this investigation was to examine the effects of
tart Montmorency cherry juice concentrate on urinary
6-sulfatoxymelatonin and sleep quality using a double-
blind, placebo-controlled, crossover design.
Following institutional ethical approval from the School of
Life Sciences Ethics Committee at Northumbria Univer-
sity, UK in accordance with the Helsinki Declaration, 20
healthy men (n = 10) and women (n = 10) volunteered to
participate. The mean (±SD) age, height, body mass and
BMI were 26.6 (±4.6) years, 1.71 (±0.10) m, 72.5 (±15.0)
kg and 24.7 (±3.5) kg m
, respectively. The age range
was restricted to 18–40 years to reduce the potential for
age-related sleep disturbances that have been reported in
older adults [13]. In addition, all volunteers were physi-
cally active and participated in moderate physical exercise
for at least 150 min/week. After being informed of the
experimental procedures, participants were asked to com-
plete a health screening questionnaire to ascertain contra-
indications to participation (prescription medicines, sleep
disturbance, special dietary habits, shift work or underlying
medical pathology), and volunteers then provided written
informed consent.
Experimental overview and study design
Participants were supplemented with a tart cherry juice
concentrate or placebo in a randomised, double-blind,
placebo-controlled, crossover study design, during normal
daily routine. Dependent variables were urinary 6-sul-
phatoxymelatonin (aMT6s), diet recall, objective activity
recorded through actigraphy (variables) and subjective
sleep quality. A schematic of the study design is presented
in Fig. 1. Initially, participants provided sequential urinary
voids across a 48 h period (days 1 and 2) in order to ana-
lyse baseline measures of aMT6s. Over the same 2-day
period, participants were issued with an activity monitor
and completed online daily diet recalls and a sleep diary
immediately following morning awakening. Participants
then continued to complete the questionnaires and diaries
and wear the activity monitors for the remainder of the trial
Following the 48-h baseline period, participants were
randomly assigned to either the tart cherry juice concen-
trate or placebo (starting on day 3) for a period of 7 days;
this was based on loading phases from previous studies
showing efficacy using cherry juice [58]. Participants
were instructed to consume two servings of either tart
cherry juice concentrate or fruit-flavoured cordial each day,
for 7 days. In the last 48 h of this supplementation period,
urine was again collected in an identical manner as pre-
viously described for the baseline period. Following a
14-day washout period, participants repeated the baseline
Eur J Nutr
and experimental period whilst consuming the other
Dietary control
All volunteers completed a dietary recall throughout the
baseline and supplementation periods. Participants were
asked to replicate their diet during the first supplementation
period as closely as possible during the second period in
order to standardise the dietary intake between trials.
Additionally, in order to isolate dietary melatonin as clo-
sely as possible, participants were issued with a list of
foods that are known to contain or influence melatonin and
were subsequently asked to abstain from consuming these
for the duration of the trial. Portions of foods thought to
contain antioxidants were totalled for each day then aver-
aged across the experimental period.
Prior to starting the experiment, participants were informed
that the trial was to ascertain the influence of two fruit con-
centrates on melatonin levels and sleep quality; however, the
nature of the trial regarding tart cherry juice concentrate was
only revealed when the study had been completed. A serving
of 30 mL of tart Montmorency cherry juice (Prunus cerasus)
concentrate (Cherry Active, Sunbury, UK) was consumed
within 30 min of wakening and 30 min before the evening
meal on each of the 7-day supplementation periods. Each
30 mL serving was estimated to contain the equivalent of
approximately 90–100 tart cherries and was diluted with
approximately 200 mL of water. An independent laboratory
(Atlas Bioscience Inc., Tuscan, AZ) conducted melatonin
analysis of the cherry juice concentrate adapting an estab-
lished HPLC method [18]. The concentration of melato-
nin was 1.42 lgmL
, which equates to a dose of
*42.6 lg/30 mL serving or *85.2 lg day
. Literature
suggests that daily melatonin doses of *0.5–5 mg confer a
positive effect in managing disturbed sleep rhythm [19].
In addition, other active compounds contained within the tart
cherry juice were verified by the aforementioned laboratory
and included anthocyanins such as malvidin, cyanidin, pe-
largonidin, peonidin, delphinidin, petunidin (total anthocy-
anin content = 9.117 mg mL
), vitamin A—as beta-
carotene (22.64 IU mL
) and vitamin C—ascorbic acid
(0.324 mg mL
The placebo was a commercially available, economy,
mixed fruit cordial (containing less than 5% fruit) that was
reported to contain no melatonin or anthocyanins and a
trace of vitamin C. Participants were instructed to take the
same dose (30 mL) diluted with *200 mL of water.
Dependent variables
Urine collection and analysis
Sequential urinary voids were collected 48-h periods to
ensure the entire circadian cycle was captured during
each part of the trial to allow for cosinor analysis that
provided measures of acrophase, mesor and amplitude.
Urine was collected in a sterilised measuring cylinder.
Void volume, time and date were recorded, before a
10 mL aliquot of urine was retained, refrigerated and
returned to the laboratory the following morning for
labelling and immediate storage at -80 °C for later anal-
ysis for urinary aMT6s.
Urinary 6-sulphatoxymelatonin, aMT6s
Urinary 6-sulphatoxymelatonin, aMT6s (the major metab-
olite of melatonin) was analysed in duplicate using a
radioimmunoassay [20]. Samples belonging to the same
participant were measured in the same assay run; the intra-
assay coefficient of variation was \8%; the limit of
detection was 0.25 ng mL
. Evaluation of aMT6s profiles
was performed using cosinor analysis, based upon the least
square approximation of the time series using a cosine
function with a period of 24 h [21]. Parameters obtained
Fig. 1 A schematic outlining
the implemented protocol.
Supplementation periods
consisted of two 30-mL
servings per day of either a tart
cherry juice concentrate of
Eur J Nutr
from this analysis included the following: acrophase time:
the time of peak aMT6s concentration or the maximum of
the fitted cosinor function; mesor: the mean aMT6s values
for all samples included in the cosinor anlaysis; and
amplitude: the difference between mesor and peak aMT6
concentrations. Acrophase time was classed as normal if it
occurred between midnight and 06:00 h [22]. ‘Goodness of
fit’ measures were used to determine the validity of the
cosinor-derived indices: (1) the % rhythm or variability
accounted for by the cosine curve: 100% rhythm = all data
points fall on the cosine curve and 0% rhythm = none of
the data points fall on the cosine curve and (2) the likeli-
hood of data points fitting a straight line as opposed to a
cosine curve, expressed as a P value. Data were considered
acceptable if the cosinor fit was significant (P B 0.05) and
the % rhythm C50% [21]. Finally, the total aMT6s
excreted per 24 h was calculated and a mean for each 48-h
collection period determined.
Polysomnography (PSG) offers the most accurate assess-
ment of sleep and sleep quality; however, given the nature
of the study, we utilised actigraphy that has been shown to
be reliable and has good agreement with PSG [23]. Par-
ticipants were issued with actigraphy that was worn on the
wrist of the non-dominant arm (Actiwatch 7, CamnTech,
Cambridge, UK). These were worn for the duration of the
study and removed only for bathing, showering or other
aquatic activities. Participants were asked to activate the
marker function on the watch when getting into bed and
when rising the following morning. Analysis was made on
sleep efficiency (SE), sleep onset latency (SOL), time in
bed (TIB), fragmentation index (FRAGI), total sleep time
(TST) and sleep efficiency total (SET); these variables
were calculated using Actiwatch software (Actiwatch,
CamnTech, Cambridge, UK). The mean values for each
sample period were used for data analysis.
Subjective measures
Online subjective sleep diaries were reported immediately
following awakening each day during both baseline and
trial periods. This commonly used self-reporting method
tool has been to be a reliable (90%) measure [24] and
allowed calculation of the following: SE, SOL, wake after
sleep onset (WASO), napping (NAP), TST and SET [25].
Statistical analyses
Values are reported as mean (±SD), unless otherwise sta-
ted. The cosinor data, total aMT6s and all quantitative
(actigraphy)- and qualitative (questionnaire)-dependent
sleep variables were analysed with a repeated measures
ANOVA (condition, placebo vs. cherry juice 2; time, pre
vs. post). In addition, 95% confidence intervals were also
determined to illustrate the magnitude of change. Finally,
baseline measures were examined for differences using a
paired samples t test. Significance was set at an alpha level
of 0.05.
Baseline measures taken before the placebo and cherry
juice trials were not different for any of the dependent
variables (P [ 0.05). All variables returned an observed
power value ranging from 0.156 to 0.999. Although we
did not quantify all the food consumption using dietary
analysis, participants reported a similar diet across the
trials. In an attempt to quantify this more fully, we
recorded the number of food portions thought to contain
antioxidants (including melatonin) across the supplemen-
tation periods, 22.8 versus 22.4 for the cherry juice and
placebo groups, respectively. A paired samples t test
showed no significant differences between groups
(t = 1.162, P = 0.259).
Urinary 6-sulphatoxymelatonin (aMT6s)
The baseline measures preceding the placebo and cherry
juice supplements were not different (t
= 0.921,
P = 0.369). The repeated measures ANOVA showed a
significant trial effect (F = 23.0, P \ 0.001). A significant
interaction (F = 23.0, P \ 0.001) was also found and
post hoc analysis revealed that the cherry juice trial was
significantly greater than baseline and placebo trials
(P \0.001; 95% CI = 2,828–5,393 ng and 2,519–5,450 ng,
respectively); there was no difference between baseline or
placebo groups (Fig. 2).
Despite the significant increase in total urinary aMT6 s,
the cosinor analysis examining circadian rhythm of aMT6s
showed no differences between trials for any variable
(Table 1). Cosinor analysis relies on a significant ‘fit’ of
the melatonin response; of the 80 sets of data collected,
22.5% (n = 18) were excluded because they did not sig-
nificantly fit according to the cosinor algorithm. Of the
remaining data, there were small non-significant rises in the
amplitude and mesor in the cherry juice trial, whilst the
acrophase remained largely unchanged throughout. A
representative example where urinary voids were collected
for a single participant at similar times of the day between
the placebo and cherry juice trials is presented in Fig. 3;
these data span the circadian changes in aMT6s over
sequential 48-h periods.
Eur J Nutr
Sleep indices: subjective questionnaire and actigraphy
There was a 100% completion rate for the sleep ques-
tionnaires. There was no differences across the different
trials for SET, SOL, TST and WASO; however, napping
time did show a significant trial and interaction effect
(F = 5.591, P = 0.029), with significantly less napping
time in the cherry juice trial compared to baseline and
the placebo trials (P B 0.031; 95% CI = 0.7–13.6 and
0.7–11.1 min, respectively), and there were no differences
between baseline measures and the placebo trial (Table 2).
Whilst all participants wore the activity monitor for the
duration of the trials, 17 out of 80 trials (21.3%) were
excluded from analysis due to missing data. There were no
differences in SOL and FRAGI; however, there was a sig-
nificant trial and interaction effect for TIB (F = 7.056,
P = 0.016) where cherry juice significantly increased time
in bed compared to both baseline and placebo trails
(P B 0.017; 95% CI = 4.5–45.2 and 4.7–40.2 min,
respectively). Furthermore, TST showed a trial and inter-
action effect (F = 11.189, P = 0.003), where the cherry
juice trial was significantly greater TST than baseline and
placebo trials (P B 0.003; 95% CI = 15.2–39.7, 14.7–63.6,
respectively). In addition, SET showed significant trial and
interaction effects (F = 5.410, P = 0.031), where the
cherry juice trial was greater than the baseline and placebo
trials (P B 0.017; 95% CI = 2.1–7.5 and 0.5–9.4, respec-
tively). A summary of these data is presented in Table 3.
The aim of this investigation was to ascertain whether the
supplementation of tart Montmorency cherry juice con-
centrate would (1) increase the urinary aMT6s content
and (2) improve the objective and subjective sleep indices
of young, healthy individuals. We hypothesised that
urinary aMT6s would rise and that sleep parameters
would improve as a consequence. This is the first inves-
tigation to demonstrate that dietary tart cherry juice
concentrate increases urinary melatonin levels and pro-
vides improved sleep time and quality in a healthy adult
The sleep diary information showed that napping time
decreased with the administration of cherry juice, whereas
the actigraphy showed an increase in TIB, TST and SET, a
global measure of sleep quality. Notwithstanding the rel-
atively low baseline SET observed from the actigraphy in
these apparently good sleepers, the cherry juice nonetheless
showed a 5–6% increase in SET, which likely to be
influenced by the significant increase in TST. In addition,
given that napping decreased and total time in bed also
increased during the cherry juice trial, this is perhaps
unsurprising. What is also interesting to note is that there
Fig. 2 Mean (±SEE) urinary melatonin (aMT6) secretion for the
group following baseline placebo (control), placebo, baseline cherry
juice (control) and cherry juice trials.Asterisk denotes that cherry
juice supplementation resulted in significantly greater aMT6s than
baseline and placebo trials (P B 0.05)
Table 1 Mean (±SD) cosinor analysis based on melatonin circadian rhythm for all experimental conditions
Baseline placebo Placebo Baseline cherry juice Cherry juice
Mesor (ng 9 h
) 17.98 (6.04) 19.17 (7.37) 18.64 (9.76) 21.59 (6.85)
Amplitude (lg 9 h
) 27.39 (15.78) 27.54 (8.37) 27.05 (10.72) 28.57 (15.01)
Acrophase (time) 4.03 (1.03) 3.55 (1.22) 4.05 (1.40) 4.01 (1.01)
Of the possible 80 data sets, 18 did not significantly fit the cosinor curve and were excluded from the analysis
Fig. 3 A representative example of a single subject’s circadian
rhythm for urinary melatonin (aMT6s) during the placebo and cherry
juice trials over sequential 48-h periods
Eur J Nutr
were non-significant trends towards decreased SOL, which
is also likely to have influenced the SET.
Only one study has investigated tart Montmorency
cherry juice and sleep parameters (a fresh pressed cherry
juice blended with apple juice, as opposed to a pure cherry
juice concentrate) [8]. They found that elderly individuals,
with moderate/severe insomnia, reported improved sleep
quality, and it was hypothesised that this was due to the
increased exogenous melatonin content afforded by the
cherry juice. Unfortunately, they did not measure melato-
nin; however, data from our investigation lend additional
evidence that improved sleep quality is mediated by the
increase in dietary melatonin contained within the cher-
ries. Interestingly, a recent addition to the literature [26]
examined the increase in melatonin content from dietary
intake of Jert Valley cherries (seven varieties, none of
which were Montmorency tart cherries). They showed that
in a very small population of middle-aged and elderly
volunteers, there was an increase in urinary melatonin and
some modest improvements in sleep parameters. This
investigation [26] based its observations on the first
morning void only, whereas all urinary voids were captured
for a 48-h period during each part of the current trial. This
approach, whilst still having limitations, allows for cosinor
analysis and tracking of the circadian rhythm and provides
a more comprehensive picture of the dietary effects of
cherries on melatonin metabolism across the course of the
day. This is especially important when one considers that
the half-life of melatonin is relatively short and it is pos-
sible to miss fluctuations in melatonin throughout the day.
Further, there is no indication in the aforementioned
studies [8, 25] of an experimental control or record of
dietary intake, which makes interpretation of the data
problematic. Although we were not able to quantify the
exact nutritional content for each subject, food intake was
estimated. Participants replicated diet as closely as possible
from trial to trial. This was based on number of portions
thought to contain antioxidants—there were no differences
between trials. Support for the efficacy of this approach can
be seen by the fact that aMT6s and sleep parameters were
unchanged in baseline and placebo trials, whereas aMT6s
was significantly elevated in the cherry juice trial. Given the
dietary control used in the current investigation, coupled
with the significant changes melatonin, we can add support
to research showing cherries [26], and specifically in this
case, Montmorency cherries improve sleep parameters in
healthy individuals, which is likely due to the increase in
dietary melatonin. These data support previous work
showing improved sleep in healthy younger adults with
exogenous melatonin supplementation [14]; but addition-
ally, it provides a potential alternative to traditional mela-
tonin supplementation in the form of a functional food.
Table 2 Subjective sleep questionnaire variables for all conditions; values are mean (±SD)
Baseline placebo Placebo Baseline cherry juice Cherry juice
SE (%) 89.3 (7.3) 91.7 (4.0) 90.0 (6.2) 91.1 (4.9)
SOL (mins) 40.3 (31.6) 39.5 (23.2) 39.8 (25.6) 34.2 (20.5)
WASO (mins) 36.0 (33.0) 19.2 (31.2) 28.8 (30.6) 27.6 (28.2)
Naps (mins) 9.0 (15.1) 7.8 (10.7) 8.6 (13.2) 1.9 (3.5)*
TST (mins) 447 (60) 476 (31) 452 (49) 475 (30)
SET (%) 88.1 (6.8) 90.4 (4.4) 89.4 (5.8) 90.7 (4.9)
SE sleep efficiency, SOL sleep onset latency, WASO wake after sleep onset, total SET sleep efficiency total, TST total sleep time
* Denotes significantly different from all other conditions (P B 0.05)
Table 3 Actigraphy variables for all conditions; values are mean (± SD)
Baseline placebo Placebo Baseline cherry juice Cherry juice
SE (%) 82.8 (15.7) 84.1 (5.8) 83.9 (7.8) 86.8 (3.6)
SOL (mins) 28.9 (21.3) 30.5 (34.8) 29.1 (26.8) 21.4 (11.1)
Time in bed (mins) 491.8 (36.7) 492.2 (40.6) 490.0 (32.9) 514.7 (17.0)*
FRAGI (AU) 36.8 (8.2) 35.2 (9.3) 35.8 (8.9) 34.2 (7.6)
TST (mins) 392 (28) 380 (49) 385 (30) 419 (22)*
SET (%) 77.5 (5.9) 77.4 (8.5) 76.8 (6.9) 82.3 (3.6)*
Of the possible 80 data sets, 17 were excluded due to technical issues
SE sleep efficiency, SOL sleep onset latency, FRAGI fragmentation index, total SET sleep efficiency total, TST total sleep time
* Denotes significantly different from all other conditions (P B 0.05)
Eur J Nutr
The secretion of melatonin is influenced by light/dark
cycles and ultimately is instrumental in the sleep/wake
cycle [13]. From a physiological perspective, given that
endogenous melatonin influences core temperature and
facilitates sleep [14], it makes the expectation tenable that
increased exogenous melatonin will further facilitate
changes in core temperature and hence be responsible for
the improvements in sleep quality. Further work examining
the potential physiological outcomes (such as core tem-
perature and EEG in polysomnographic paradigms) from
exogenous melatonin, specifically from functional foods,
would be useful additions to the literature. In an attempt to
elucidate the relationship between the change in SET and
the change in melatonin, we conducted a Pearson’s corre-
lation coefficient analysis and found that there was a
modest relationship (r = 0.416, P [ 0.05), indicating that
other factors may influence the variables associated with
sleep quality. Importantly, a limitation with our data is that
*21% of the actigraphy data were missing, which may
have influenced this correlation and also the non-significant
trends in other actigraphy-dependent variables. Further-
more, 50% of our sample was women, and it is conceivable
that they were in different stages of the menstrual cycle,
which may also influence core temperature and hence the
propensity for sleep disturbance [27]. Future research
might wish to consider this issue in future experiments.
Melatonin is not the only candidate mechanism, given
that sleep regulation is also influenced by pro-inflammatory
cytokines [17]. Tart cherries have been shown to contain
numerous phenolic compounds that have anti-inflammatory
and antioxidant properties that can increase antioxidant
capacity [5, 26]. Furthermore, cherry juice has been shown
to decrease oxidative stress and inflammation following
strenuous exercise [5] making it possible that these anti-
oxidant and/or anti-inflammatory properties modulated
indices of sleep in this study, although this remains to be
demonstrated in an experimental model.
It has been previously speculated that the positive
effects on sleep seen from tart cherries might be due to
improvements in circadian regulation [8]. We observed no
changes in mesor, amplitude or acrophase, although there
was a trend towards a higher mesor (essentially equating to
the mean value across the circadian cycle). This is perhaps
not surprising given that the total urinary melatonin did
increase with cherry juice supplementation. An obvious
difference with the previous work lies within the subject
populations; Pigeon et al. [8] used older adults suffering
from moderate/severe insomnia and did not measure cir-
cadian rhythm or melatonin, whereas the current investi-
gation used asymptomatic younger adults (B37 years) and
did measure circadian rhythm and melatonin. Conceivably,
cherries might help regulate circadian rhythm in those with
disturbed sleep [8]; however, our evidence shows (from
cosinor analysis) that despite increased total sleep time and
improved sleep quality, this is not the case in asymptom-
atic, healthy younger adults. Notwithstanding this, aMT6s
levels are increased with tart cherry juice consumption, but
an investigation that examines elderly individuals, perhaps
with disturbed sleep, that incorporates measures of circa-
dian rhythms and sleep quality would be a valuable addi-
tion to the literature.
In conclusion, this is the first study to show direct evi-
dence that dietary supplementation with a tart Montmorency
cherry juice concentrate increases circulating melatonin and
can provide modest improvements in sleep time and quality
in healthy adults with no reported disturbed sleep. Although
the interaction of other phytochemicals cannot be com-
pletely ruled out, these data provide a mechanism of action
for the previously conjectural reports of improved sleep
quality with cherry juice supplementation. Subsequently,
Montmorency tart cherry juice concentrate might therefore
present a suitable adjunct intervention for disturbed sleep
across a number of scenarios in healthy and symptomatic
Acknowledgments Gratitude is extended to Kelly Mitcheson for
her help in data collection and to CherryActive (Sunbury, UK) for
donating the cherry juice concentrate.
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... Significant levels of FMT have been noted in some food products, such as cherries and walnuts [16,17]. In experimental studies, FMT consumption has been associated with an increase in blood MT levels [17,18], improved sleep function [19][20][21][22][23], and psychoemotional state [24]. However, in some studies [25,26], FMT consumption had no positive effect on sleep function. ...
... Our study also showed that schoolchildren and university students who consume more FMT during the day have higher sleep quality. These data are consistent with previously published data on FMT's positive effect on sleep function [19][20][21][22][23]. In particular, MT-rich foods for dinner and breakfast have previously been shown to increase sleep duration and efficiency [19,21,22] as well as reduce sleep latency [19] in adults and the elderly. ...
... These data are consistent with previously published data on FMT's positive effect on sleep function [19][20][21][22][23]. In particular, MT-rich foods for dinner and breakfast have previously been shown to increase sleep duration and efficiency [19,21,22] as well as reduce sleep latency [19] in adults and the elderly. One study [22] found that drinking cherry juice concentrate with high MT content in the morning and evening for a week increases the amplitude and mesor, but not the phase of the 24-h rhythm of MT metabolite excretion in the urine. ...
Full-text available
Food is an important source of melatonin (MT), which belongs to a group known as chronobiotics, a class of substances that affect the circadian system. Currently, no studies have been conducted on how the consumption of foods containing MT (FMT) is associated with indicators characterizing the human circadian system. In this study, we tested the hypothesis that FMT consumption is associated with chronotype and social jetlag. A total of 1277 schoolchildren and university students aged M (SD) 19.9 (4.1) years (range: 16–25 years; girls: 72.8%) participated in a cross-sectional study. Each participant completed an online questionnaire with their personal data (sex, age, height, weight, waist circumference, and academic performance) and a sequence of tests to assess their sleep–wake rhythm (the Munich Chronotype Questionnaire), sleep quality (the Pittsburgh Sleep Quality Index), and depression level (the Zung Self-Rating Depression Scale). Study participants also completed a modified food frequency questionnaire that only included foods containing MT (FMT). They were asked how many foods containing MT (FMT) they had eaten for dinner, constituting their daily serving, in the past month. The consumption of foods containing MT (FMT) during the day (FMTday) and at dinner (FMTdinner) was assessed using this test. Multiple regression analyses were performed to assess the association between the studied indicators. We found that higher FMTday values were associated with early chronotype (β = −0.09) and less social jetlag (β = −0.07), better sleep quality (β = −0.06) and lower levels of depression (β = −0.11), as well as central adiposity (β = −0.08). Higher FMTdinner values were associated with a lower risk of central adiposity (β = −0.08). In conclusion, the data obtained confirm the hypothesis that the consumption of foods containing MT (FMT) is associated with chronotype and social jetlag in adolescents and young adults.
... Many pharmacological efects of these substances are mentioned above. Studies in the literature have shown that a fruit juice is usually given in order to reduce oxidative stress due to heavy exercise [20][21][22][23][24][25]. Te use of black currant, cherry, grape, watermelon, blueberry, pomegranate, and banana has been reported in detail in the studies on athletes [20][21][22][23][24][25]. ...
... Studies in the literature have shown that a fruit juice is usually given in order to reduce oxidative stress due to heavy exercise [20][21][22][23][24][25]. Te use of black currant, cherry, grape, watermelon, blueberry, pomegranate, and banana has been reported in detail in the studies on athletes [20][21][22][23][24][25]. It has been reported that drinking pomegranate juice before Olympic-style weightlifting sessions reduces malondialdehyde levels and improves the enzymatic reactions of catalase and glutathione peroxidase [26]. ...
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Background. In this study, the effects of pomegranate-black carrot juice mixture on serum and erythrocytes of sedentary individuals who had exhaustion test were investigated. Methods. A total of 20 men voluntarily participated in the study. Blood samples were obtained from participants on three conditions. First, before the study, blood samples of participants were collected (baseline). Second, the same participants performed in the 20-meter shuttle run test for 1 week each day and were subjected to oxidative stress. Lastly, the same participants were given a mixture of pomegranate-black carrot juices (100 ml/100 ml) for a week, 45 minutes prior to the 20-meter shuttle run test, and the stress + supplement was performed. Blood samples were taken at the end of each process. Results. In the erythrocytes, while the oxidative stress condition malondialdehyde (MDA) level and carbonic anhydrase (CA) enzyme activity levels increased compared to the baseline, reduced glutathione (GSH) level, glutathione reductase (GR), and glutathione S-transferase (GST) enzyme activity levels decreased. In stress + supplement conditions, while GSH and GR levels increased according to oxidative stress conditions, CA and MDA levels decreased. While the lactate dehydrogenase (LDH) level of the oxidative stress condition increased compared to the baseline, the LDH level of the stress + supplement decreased compared to the oxidative stress condition. Conclusions. Our results showed that the level of oxidative stress in subjects exposed to the exhaustion test decreased with the mixture of pomegranate-black carrot juices.
... 16 It is likely that nutritional interventions and supplements may help to alleviate menopause-related sleep disturbances, since these interventions have been shown to improve relevant aspects of sleep. For instance, relative to placebo, tart cherry juice has been shown to improve objective sleep quantity and quality 18 ; tryptophan-rich foods have also been shown to improve subjective and objective sleep quantity and quality. 19 Therefore, nutritional interventions and supplements are likely to represent one route by which menopause-related sleep disturbances can be treated, or alternatively, used to improve sleep. ...
... In terms of specific future research directions, aside from the high-quality trials of the specific interventions identified in the previous section, perhaps one of most important is that ideally, nutritional interventions should have a sound underlying mechanistic justification in relation to the target symptom (eg, valerian may be sleep-promoting due to its impact upon adenosine A1 and GABA-A receptors 90 ). It is perhaps surprising that interventions which have been shown to improve sleep in other groups have not yet been trialled in relation to menopause-related sleep disturbances, such as tart cherry juice, 18 which does appear to improve objective sleep and promote exogenous melatonin levels, or tryptophan-rich foods. 19 These could potentially be trialed in the short term. ...
Full-text available
Context Sleep disturbances are a core symptom of menopause, which refers to the permanent cessation of menstrual periods. Nutritional interventions may alleviate menopause-related sleep disturbances, as studies have shown that certain interventions (eg, tart cherry juice, or tryptophan-rich foods) can improve relevant aspects of sleep. Objective The aim of this systematic review was to examine the effect of nutritional interventions for menopause-related sleep disturbances, in order to inform the subsequent development of specific interventional trials and assess their potential as a treatment for menopause-related sleep disturbances. Data Sources Published studies in English were located by searching PubMed and PsycArticles databases (until September 15, 2022). Data Extraction Following full-text review, a final total of 59 articles were included. The search protocol was performed in accordance with PRISMA guidelines. Data Analysis A total of 37 studies reported that a nutritional intervention improved some aspect of sleep, and 22 studies observed no benefit. Most (n = 24) studies recruited postmenopausal women, 18 recruited menopausal women, 3 recruited perimenopausal women, and 14 recruited women from multiple groups. The majority of the studies were of low methodological quality. Due to the heterogeneity of the studies, a narrative synthesis without meta-analysis is reported. Conclusion Despite the large heterogeneity in the studies and choice of intervention, the majority of the identified studies reported that a nutritional intervention did benefit sleep, and that it is mainly subjective sleep that is improved. More high-quality, adequately powered, randomized controlled trials of the identified nutritional interventions are necessary. Systematic Review Registration PROSPERO registration no. CRD42021262367.
... For a period of six weeks, participants assigned to this group will consume 60 mL of Montmorency tart cherry concentrate (Montmorency Tart Cherry Juice Concentrate, King Orchards, Kewadin, MI, USA) each day [36][37][38]. The concentrate will then be diluted with 100 mL of water to make each 30 mL serving into a 130 mL beverage. ...
... A 30 mL dose of Montmorency tart cherry concentrate includes 80 Kcal, 19 g of carbohydrates, of which 15 g are sugars, 1.1 g of protein, and 1 g of fibre, according to the manufacturer. Previous phytochemical analyses have shown that 30 mL of Montmorency tart cherry concentrate contains 9.117 mg/mL of anthocyanins and 6.63 total phenolics/mL (expressed as gallic acid equivalents) [38,39]. However, to quantitatively assess the anthocyanin and phenolic contents of the supplement batch that is utilized in this trial, a phytochemical content analysis of the Montmorency tart cherry concentrate batch will be completed by the manufacturer. ...
Full-text available
Ulcerative colitis, characterized by its relapsing and remissive nature, significantly impacts per-ception, body image, and overall quality of life. The associated financial burden underscores the need for alternative treatment approaches with fewer side effects, alongside pharmaceutical in-terventions. Montmorency tart cherries, rich in anthocyanins, have emerged as a potential natural anti-inflammatory agent for ulcerative colitis. This manuscript outlines the study protocol for a randomized placebo-controlled trial investigating the effects of Montmorency tart cherry in in-dividuals with ulcerative colitis. The trial aims to recruit 40 participants with mild to moderate disease activity randomly assign them to either a Montmorency tart cherry or placebo group. The intervention will span 6-weeks, with baseline and 6-week assessments. The primary outcome measure is the Inflammatory Bowel Disease Quality of Life Questionnaire. Secondary outcomes include other health-related questionnaires, blood biomarkers, and fecal samples. Statistical analysis will adhere to an intention-to-treat approach using linear mixed effect models. Ethical approval will be obtained from the University of Hertfordshire, and the trial has been registered as a clinical trial (NCT05486507). The trial findings will be disseminated through a peer-reviewed publication in a scientific journal.
... Type-Dosage consumption timeC Effect Lin, 2011 [155] two kiwifruit hour before bedtime ↑The property of sleep -↑ TST Valtonen, 2005 [156] 100 g or of 500 g(a large dose) normal commercial milk daily dose no effect on sleep Garrido, 2010 [157] Sour cherry juice twice a day ↓insomnia Howatson, 2012 [158] Sour cherry juice (2 servings of 30 ml concentrate) ↑SE-↑ TST ↓daytime napping SE: sleep efficiency, TST: total sleep time, ↑ increase, ↓ decrease. ...
... Some studies observed that a healthy dietary pattern, with a large consumption of fruit, vegetables, fish and fibers, and regular meals, is associated to a better sleep quality (139,(148)(149)(150). The consumption of specific variety of cherries or their juice, which are rich in melatonin and serotonin, is often reported to be associated to a better sleep (151,152). Vegetarians seem to have less sleep disorder, quantified with a lower Athens Insomnia Scale score (given by the sum of the scores for difficulty in sleep induction, awakenings during the night, earlymorning awakening, total sleep time, overall quality of sleep and day functioning) and lower diurnal sleepiness, than non-vegetarians, and this is particularly evident in women (153). Anyway, the unprocessed red meat is not clearly related to a better or a poorer sleep (148). ...
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Sleep disturbances are an emerging risk factor for metabolic diseases, for which the burden is particularly worrying worldwide. The importance of sleep for metabolic health is being increasingly recognized, and not only the amount of sleep plays an important role, but also its quality. In this review, we studied the evidence in the literature on macronutrients and their influence on sleep, focusing on the mechanisms that may lay behind this interaction. In particular, we focused on the effects of macronutrients on circadian and homeostatic processes of sleep in preclinical models, and reviewed the evidence of clinical studies in humans. Given the importance of sleep for health, and the role of circadian biology in healthy sleep, it is important to understand how macronutrients regulate circadian clocks and sleep homeostasis.
... At the same time, it is known that some foods are sources of chronobiotics, biologically active substances such as melatonin (MT), which have a direct effect on the function of the CS and thus can increase the synchronization of the circadian rhythms (Arendt and Skene 2005). Convincing experimental data have now been obtained on the positive effect of food MT or its precursor tryptophan on sleep function (Garrido et al. 2010;Pigeon et al. 2010;Lin et al. 2011;Howatson et al. 2012;Losso et al. 2018), well-being (Bravo et al. 2013), and health (Nagata et al. 2021) in young and elderly people. ...
The study examined eating timing, diet, and sleep phases in people with social jetlag (SJL). SJL was associated with a higher incidence rate of eating jetlag, eating phase delays, an increase in calorie intake after 9 p.m., a decrease in dietary fiber intake for brakfast, and melatonin-containing product consumption for dinner. People with SJL had a reduction in total sleep and light sleep phase duration by 60 and 36 min on work/school days and an increase in total sleep and rapid eye movement sleep duration by 66 and 60 min on weekends, respectively. People consuming foods with more melatonin for dinner showed a decrease in SJL by 54 min and an increase in total sleep and the deep sleep phase duration by 66 and 30 min, respectively. Thus, the consumption of melatonin-containing foods for dinner is associated with a decrease in circa-dian misalignment and an improvement in sleep quality. ARTICLE HISTORY
Low mental energy can contribute to decreased productivity, altered life balance, decreased physical performance, and ultimately affect quality of life. As such, there is a great demand for food and beverage products that positively impact mental energy. Numerous products claim to alter mental energy making continued review of the scientific evidence critical. The objective of this study was to conduct a scoping review of randomized controlled trials to evaluate the effect of 18 dietary ingredients on mental energy outcomes in adults without severe disease. Methods: A literature search, completed using PubMed, resulted in the identification of 2261 articles, 190 of which met eligibility from initial abstract review. Full-text review was completed on the 190 studies which resulted in 101 articles that fully met eligibility for inclusion in this study. The search strategy for two ingredients did not yield any eligible studies, leaving studies for 16 ingredients that were extracted and summarized by reported significantly improved outcomes for cognition, mood and perceived feelings, and sleep assessments. The preliminary results for several dietary ingredients directionally suggested a mental energy benefit (≥20% of outcomes), including ashwagandha, chamomile, dark chocolate, ginseng, green tea, lavender, lion's mane mushroom, maca, tart cherries, turmeric, and valerian root. The results of this scoping review suggest that of the 16 dietary ingredients reviewed, 11 may be promising for further exploration on their potential benefits in supporting mental energy. Given consumer demand and market growth for food and beverage products that positively impact mental energy; continued efforts in assessment method alignment and additional evaluation in well-designed trials is warranted. KEY TEACHING POINTSOf the 16 dietary ingredients reviewed, 11 (ashwagandha, chamomile, dark chocolate, ginseng, green tea, lavender, lion's mane mushroom, maca, melatonin foods, turmeric, and valerian root) may be promising for further exploration on their potential mental energy benefits.Dark chocolate, ginseng, ashwagandha, and lion's mane mushroom were the most promising ingredients for further evaluation in the cognition domain of the ingredients evaluated.Turmeric, maca, lavendar, and ashwagandha were the most promising ingredients for further evaluation in the mood and perceived feelings domain of the ingredients evaluated.Ashwagandha, chamomile, green tea, melatonin foods, valerian root were the most promising ingredients for further evaluation in the sleep domain of the ingredients evaluated.Additional, well-designed, consistent, clinical trials and systematic reviews are warranted as the challenge of heterogeneity in mental energy study design remains.
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Long distance running causes acute muscle damage resulting in inflammation and decreased force production. Endurance athletes use NSAIDs during competition to prevent or reduce pain, which carries the risk of adverse effects. Tart cherries, rich in antioxidant and anti-inflammatory properties, may have a protective effect to reduce muscle damage and pain during strenuous exercise. This study aimed to assess the effects of tart cherry juice as compared to a placebo cherry drink on pain among runners in a long distance relay race. The design was a randomized, double blind, placebo controlled trial. Fifty-four healthy runners (36 male, 18 female; 35.8 +/- 9.6 yrs) ran an average of 26.3 +/- 2.5 km over a 24 hour period. Participants ingested 355 mL bottles of tart cherry juice or placebo cherry drink twice daily for 7 days prior to the event and on the day of the race. Participants assessed level of pain on a standard 100 mm Visual Analog Scale (VAS) at baseline, before the race, and after the race. While both groups reported increased pain after the race, the cherry juice group reported a significantly smaller increase in pain (12 +/- 18 mm) compared to the placebo group (37 +/- 20 mm) (p < .001). Participants in the cherry juice group were more willing to use the drink in the future (p < 0.001) and reported higher satisfaction with the pain reduction they attributed to the drink (p < 0.001). Ingesting tart cherry juice for 7 days prior to and during a strenuous running event can minimize post-run muscle pain.
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This study ascertained whether a proprietary tart cherry juice blend (CherryPharm, Inc., Geneva, NY, USA) associated with anecdotal reports of sleep enhancement improves subjective reports of insomnia compared to a placebo beverage. The pilot study used a randomized, double-blind, crossover design where each participant received both treatment and placebo for 2 weeks with an intervening 2-week washout period. Sleep continuity (sleep onset, wake after sleep onset, total sleep time, and sleep efficiency) was assessed by 2-week mean values from daily sleep diaries and disease severity by the Insomnia Severity Index in a cohort of 15 older adults with chronic insomnia who were otherwise healthy. The tart cherry juice beverage was associated with statistically significant pre- to post-treatment improvements on all sleep variables. When compared to placebo, the study beverage produced significant reductions in insomnia severity (minutes awake after sleep onset); no such improvements were observed for sleep latency, total sleep time, or sleep efficiency compared to placebo. Effect sizes were moderate and in some cases negligible. The results of this pilot study suggest that CherryPharm, a tart cherry juice blend, has modest beneficial effects on sleep in older adults with insomnia with effect sizes equal to or exceeding those observed in studies of valerian and in some, but not all, studies of melatonin, the two most studied natural products for insomnia. These effects, however, were considerably less than those for evidence-based treatments of insomnia: hypnotic agents and cognitive-behavioral therapies for insomnia.
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This investigation determined the efficacy of a tart cherry juice in aiding recovery and reducing muscle damage, inflammation and oxidative stress. Twenty recreational Marathon runners assigned to either consumed cherry juice or placebo for 5 days before, the day of and for 48 h following a Marathon run. Markers of muscle damage (creatine kinase, lactate dehydrogenase, muscle soreness and isometric strength), inflammation [interleukin-6 (IL-6), C-reactive protein (CRP) and uric acid], total antioxidant status (TAS) and oxidative stress [thiobarbituric acid reactive species (TBARS) and protein carbonyls] were examined before and following the race. Isometric strength recovered significantly faster (P=0.024) in the cherry juice group. No other damage indices were significantly different. Inflammation was reduced in the cherry juice group (IL-6, P<0.001; CRP, P<0.01; uric acid, P<0.05). TAS was ~10% greater in the cherry juice than the placebo group for all post-supplementation measures (P<0.05). Protein carbonyls was not different; however, TBARS was lower in the cherry juice than the placebo at 48 h (P<0.05). The cherry juice appears to provide a viable means to aid recovery following strenuous exercise by increasing total antioxidative capacity, reducing inflammation, lipid peroxidation and so aiding in the recovery of muscle function.
The anthocyanin contents of Balaton and Montmorency cherries were compared. The results indicate that both cherries contain identical anthocyanins. However, Balaton contains approximately six times more anthocyanins than does Montmorency. Also, hydrolysis of the total anthocyanins and subsequent gas chromatographic (GC) and nuclear magnetic resonance (NMR) experiments with the resulting products indicated that both varieties contain only one aglycon cyanidin. This observation contrasts with existing reports of the presence of peonidin glycosides in Montmorency cherry. Results of the present study suggest that the anthocyanins in Balaton and Montmorency cherries are anthocyanin 1 [3-cyanidin 2‘‘-O-β-d-glucopyranosyl-6‘‘-O-α-l-rhamnopyranosyl-β-d-glucopyranoside], anthocyanin 2 [3-cyanidin 6‘‘-O-α-l-rhamnopyranosyl-β-d-glucopyranoside], and anthocyanin 3 [3-cyanidin O-β-d-glucopyranoside]. Keywords: Prunus cerasus; fruit; Balaton; Montmorency; anthocyanin; cyanidin; cyanidin glucoside; quantification and characterization
Sleep is often assessed in circadian rhythm studies and long-term monitoring is required to detect any changes in sleep over time. The present study aims to investigate the ability of the two most commonly employed methods, actigraphy and sleep logs, to identify circadian sleep/wake disorders and measure changes in sleep patterns over time. In addition, the study assesses whether sleep measured by both methods shows the same relationship with an established circadian phase marker, urinary 6-sulphatoxymelatonin. A total of 49 registered blind subjects with different types of circadian rhythms were studied daily for at least four weeks. Grouped analysis of all study days for all subjects was performed for all sleep parameters (1062–1150 days data per sleep parameter). Good correlations were observed when comparing the measurement of sleep timing and duration (sleep onset, sleep offset, night sleep duration, day-time nap duration). However, the methods were poorly correlated in their assessment of transitions between sleep and wake states (sleep latency, number and duration of night awakenings, number of day-time naps). There were also large and inconsistent differences in the measurement of the absolute sleep parameters. Overall, actigraphs recorded a shorter sleep latency, advanced onset time, increased number and duration of night awakenings, delayed offset, increased night sleep duration and increased number and duration of naps compared with the subjective sleep logs. Despite this, there was good agreement between the methods for measuring changes in sleep patterns over time. In particular, the methods agreed when assessing changes in sleep in relation to a circadian phase marker (the 6-sulphatoxymelatonin (aMT6s) rhythm) in both entrained (n= 30) and free-running (n= 4) subjects.
Montmorency cherries contain high levels of polyphenolic compounds including flavonoids and anthocyanins possessing antioxidant and anti-inflammatory effects. We investigated whether the effects of intensive unilateral leg exercise on oxidative damage and muscle function were attenuated by consumption of a Montmorency cherry juice concentrate using a crossover experimental design. Ten well-trained male overnight-fasted athletes completed two trials of 10 sets of 10 single-leg knee extensions at 80% one-repetition maximum. Trials were separated by 2 wk, and alternate legs were used in each trial. Participants consumed each supplement (CherryActive® (CA) or isoenergetic fruit concentrate (FC)) for 7 d before and 48 h after exercise. Knee extension maximum voluntary contractions (MVC) were performed before, immediately after, and 24 and 48 h after the damaging exercise. Venous blood samples were collected at each time point, and serum was analyzed for creatine kinase (CK) activity, nitrotyrosine, high-sensitivity C-reactive protein, total antioxidant capacity, and protein carbonyls (PC). Two-way repeated-measures ANOVA were used for statistical analysis of the data. MVC force recovery was significantly faster (24 h: CA 90.9% ± 4.2% of initial MVC vs FC 84.9% ± 3.4% of initial MVC; 48 h: CA 92.9% ± 3.3% of initial MVC vs FC 88.5% ± 2.9% of initial MVC (mean ± SEM); P < 0.05) after CA than FC consumption. Only serum CK and PC increased significantly from baseline, peaking 24 h after exercise (P < 0.001). The exercise-induced increase in CK activity was not different between trials. However, both the percentage (24 h after: CA 23.8% ± 2.9% vs FC 82.7% ± 11.7%; P = 0.013) and absolute (24 h after: CA 0.31 ± 0.03 nmol·mg(-1) protein vs FC 0.60 ± 0.08 nmol·mg(-1) protein; P = 0.079) increase in PC was lower in CA than FC trials. Montmorency cherry juice consumption improved the recovery of isometric muscle strength after intensive exercise perhaps owing to the attenuation of the oxidative damage induced by the damaging exercise.
Tryptophan, serotonin, and melatonin, present in Jerte Valley cherries, participate in sleep regulation and exhibit antioxidant properties. The effect of the intake of seven different Jerte Valley cherry cultivars on the sleep-wake cycle, 6-sulfatoxymelatonin levels, and urinary total antioxidant capacity in middle-aged and elderly participants was evaluated. Volunteers were subjected to actigraphic monitoring to record and display the temporal patterns of their nocturnal activity and rest. 6-sulfatoxymelatonin and total antioxidant capacity were quantified by enzyme-linked immunosorbent assay and colorimetric assay kits, respectively. The intake of each of the cherry cultivars produced beneficial effects on actual sleep time, total nocturnal activity, assumed sleep, and immobility. Also, there were significant increases in 6-sulfatoxymelatonin levels and total antioxidant capacity in urine after the intake of each cultivar. These findings suggested that the intake of Jerte Valley cherries exerted positive effect on sleep and may be seen as a potential nutraceutical tool to counteract oxidation.
The ability of melatonin to shift biological rhythms is well known. As a result, melatonin has been used in the treatment of various circadian rhythm sleep disorders, such as advanced and delayed sleep phase disorders, jet lag and shiftwork disorder. The current evidence for melatonin being efficacious in the treatment of primary insomnia is less compelling. The development of agents that are selective for melatonin receptors provides opportunity to further elucidate the actions of melatonin and its receptors and to develop novel treatments for specific types of sleep disorders. The agonists reviewed here - ramelteon, tasimelteon and agomelatine - all appear to be efficacious in the treatment of circadian rhythm sleep disorders and some types of insomnia. However, further studies are required to understand the mechanisms of action, particularly for insomnia. Clinical application of the agonists requires a good understanding of their phase-dependent properties. Long-term effects of melatonin should be evaluated in large-scale, independent randomized controlled trials.