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Nighttime eating, particularly before bed, has received considerable attention. Limiting and/or avoiding food before nighttime sleep has been proposed as both a weight loss strategy and approach to improve health and body composition. Indeed, negative outcomes have been demonstrated in response to large mixed meals in populations that consume a majority of their daily food intake during the night. However, data is beginning to mount to suggest that negative outcomes may not be consistent when the food choice is small, nutrient-dense, low energy foods and/or single macronutrients rather than large mixed-meals. From this perspective, it appears that a bedtime supply of nutrients can promote positive physiological changes in healthy populations. In addition, when nighttime feeding is combined with exercise training, any adverse effects appear to be eliminated in obese populations. Lastly, in Type I diabetics and those with glycogen storage disease, eating before bed is essential for survival. Nevertheless, nighttime consumption of small (~150 kcals) single nutrients or mixed-meals does not appear to be harmful and may be beneficial for muscle protein synthesis and cardiometabolic health. Future research is warranted to elucidate potential applications of nighttime feeding alone and in combination with exercise in various populations of health and disease.
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Nutrients 2015, 7, 2648-2662; doi:10.3390/nu7042648
nutrients
ISSN 2072-6643
www.mdpi.com/journal/nutrients
Review
The Health Impact of Nighttime Eating: Old and
New Perspectives
Amber W. Kinsey 1 and Michael J. Ormsbee 1,2,*
1 Institute of Sports Sciences & Medicine, Department of Nutrition, Food and Exercise Sciences,
Florida State University, Tallahassee, FL 32306, USA; E-Mail: awk10d@my.fsu.edu
2 Discipline of Biokinetics, Exercise and Leisure Sciences, University of KwaZulu-Natal,
Durban 4041, South Africa
* Author to whom correspondence should be addressed; E-Mail: mormsbee@fsu.edu;
Tel.: +1-850-644-4793; Fax: +1-850-645-5000.
Received: 25 January 2015 / Accepted: 2 April 2015 / Published: 9 April 2015
Abstract: Nighttime eating, particularly before bed, has received considerable attention.
Limiting and/or avoiding food before nighttime sleep has been proposed as both a weight
loss strategy and approach to improve health and body composition. Indeed, negative
outcomes have been demonstrated in response to large mixed meals in populations that
consume a majority of their daily food intake during the night. However, data is beginning
to mount to suggest that negative outcomes may not be consistent when the food choice is
small, nutrient-dense, low energy foods and/or single macronutrients rather than large
mixed-meals. From this perspective, it appears that a bedtime supply of nutrients can
promote positive physiological changes in healthy populations. In addition, when nighttime
feeding is combined with exercise training, any adverse effects appear to be eliminated in
obese populations. Lastly, in Type I diabetics and those with glycogen storage disease, eating
before bed is essential for survival. Nevertheless, nighttime consumption of small (~150 kcals)
single nutrients or mixed-meals does not appear to be harmful and may be beneficial for
muscle protein synthesis and cardiometabolic health. Future research is warranted to
elucidate potential applications of nighttime feeding alone and in combination with exercise
in various populations of health and disease.
Keywords: nighttime eating; health; metabolism
OPEN ACCESS
Nutrients 2015, 7 2649
1. Introduction
Nighttime eating, particularly before bed, is a topic that has received considerable media attention in
recent years. Over the past decades it was thought that health and weight conscious individuals should
limit and/or avoid food in the hours close to nighttime sleep because it would negatively impact health
and body composition. Ultimately, this may increase the risks for cardiometabolic diseases such as
obesity and diabetes. However, recent studies investigating the impact of pre-sleep nutrient intake have
reported positive physiological outcomes in various populations. This review will examine the factors
that have contributed to previous opinions on the health impact of nighttime eating and explore new
evidence suggesting that our understanding of nighttime eating may need to be modified based on the
content and quantity of the food consumed during this time.
2. Effect of Nighttime Eating: An Old Perspective
The arguments in favor of limiting and/or avoiding food intake late in the night are supported by data
demonstrating diurnal variations in glucose tolerance [1], gastric emptying [2], resting energy
expenditure [3]. Moreover, in healthy normal weight men, it has been demonstrated that the postprandial
metabolic response to identical meals changes throughout the day [4,5]. For instance, when identical
meals (~544 kcals; 15% protein, 35% fat, 50% carbohydrate) are consumed either in the morning,
afternoon, or night, the thermic response to that meal appears to be the lowest with nighttime intake [4].
Similarly, studies in free-living healthy adults have shown that meal satiety also varies with time of day
and that food intake during the night is less satiating and leads to greater daily caloric intake compared
to food consumed in the morning hours [6,7]. Collectively, these studies demonstrate that the fate of
ingested nutrients changes throughout the day and that nighttime intake, when compared to daytime
intake, may lead to over-eating and weight gain with potential metabolic consequences. In light of this,
it has been suggested that food consumed at night, prior to sleep, may have adverse effects on health.
While data from animal studies appear to support this concept [8,9], not all studies concur [10]. In
human trials, populations of shift workers [11], those with the Night Eating Syndrome (NES; consume
a large percentage of total daily calories after dinner) [12], and epidemiological data [13–17] suggest
that consuming a majority of daily nutrients in the evening may have adverse health consequences (see
the following references for thorough reviews on shiftwork [11,18] and NES [19])). Briefly, regarding
shiftwork (characterized by irregular work hours to provide service throughout a 24 h day), available data
suggest that shiftwork, but more so night shiftwork, is a risk factor for negative health outcomes [11,18].
For example, it has been shown that night shift workers tend to have a higher prevalence of
overweightness, abdominal obesity [20], elevated triglycerides, dyslipidemia, impaired glucose
tolerance [21–25], and decreased kidney function [26] compared to day workers. In a study of simulated
night shiftwork in normal weight women, reductions in both total daily energy expenditure and the
thermic effect of dinner were highlighted as contributing mechanisms for weight gain, obesity and
impaired health as a result of shiftwork [27]. Thus, these data demonstrate an increased cardiometabolic
risk with night shiftwork.
Similarly, NES is associated with obesity in some studies [16,28,29]. It is unclear, however, as to
whether obesity is a consequence or cause of NES. Compared to those who do not eat late at night,
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individuals with NES consume a larger portion of their total calories at night (≥50% after dinner) and
have higher overall daily and evening caloric intake in some [30,31], but not all cases [32–34]. Likewise,
those with NES have higher 24 h respiratory quotient indicative of greater carbohydrate oxidation and
less fat oxidation [35] compared to those without NES. In addition, those with NES consume double the
amount of carbohydrate and protein and four times the fat [32] in daily meals compared to those without
NES. It is practical to assume that these behaviors would predispose night eaters to weight gain,
particularly if food is consumed in chronic excess [36]. However, not all studies report differences in
daily caloric intake between night eaters and controls [3234] and, it is interesting to note that NES is also
present in normal-weight/non-obese individuals [12,30,31,37,38]. The possibility of the non-obese night
eaters engaging in compensatory weight maintenance behaviors (e.g., exercise) cannot be ignored [31] as
this would be a plausible explanation for any weight-related differences observed. It is also possible that
NES may be a precursor to obesity as one study found that the only difference in NES characteristics
between obese and non-obese adults was that the non-obese night eaters were significantly younger [37]
suggesting that in the long-term, NES may lead to obesity. Others have found that night eating impairs
weight loss attempts [39] and is only associated with weight gain in already-obese individuals [13].
These data from shift workers and NES populations provide some evidence to suggest that consuming
the majority of daily nutrients late in the evening may have health consequences. However, this concept
cannot be fully understood without considering, the influence of sleep, or lack thereof. An inverse
relationship exists between sleep duration and body mass index with a greater likelihood of obesity in
those reporting less than 7–9 h of sleep each night [40]. Indeed, both shift workers [41] and individuals
with NES [30] report higher levels of subjective sleep disturbances (short sleep, reduced sleep quality,
difficulty falling asleep) compared to their respective counterparts. Sleep duration plays a significant
role in human behavior [42] and, while speculative, when the duration of sleep is short it is likely that
there are just more opportunities (awake hours) to eat and, in the long term, promote unfavorable body
composition changes.
Indeed, some epidemiological data suggests that consuming a higher proportion of calories later in
the day, as opposed to earlier in the day, is associated weight gain [13–17]. However, not all studies
agree [12,36,38,43]. It is important to note that several inconsistencies exist in the research examining
the effect of late evening caloric intake and body weight. Some of these discrepancies include, but are
not limited to: (1) differences in the calories consumed within a specified time frame (i.e., intake after
5 pm [44] vs. 8 pm [14], (2) whether it constitutes a portion of the dinner meal [12] or solely post-dinner
intake, and (3) whether the individual wakes up from sleep to eat [12]. Despite these inconsistencies it
is evident that consuming large quantities of food (binge eating) in the late evening may have adverse
health implications.
3. Effect of Nighttime Eating: A New Perspective
As demonstrated above, consuming large meals or the majority of daily nutrients late in the evening
may increase susceptibility to obesity and other cardiometabolic diseases. While this may hold true when
large quantities of food intake occurs at night, data is beginning to mount to suggest that this finding is not
consistent if the food choice is altered to favor small, nutrient-dense, low energy foods and/or single
macronutrients (<200 kcals) [4550]. In fact, recent studies have examined the impact of low-energy
Nutrients 2015, 7 2651
nutrient intake that occurs in close proximity to sleep and reported positive findings [4550]. Conversely,
one study [51] compared the impact of a 200 calorie snack (carbohydrate, 20.6 ± 2.6 g; protein,
2.6 ± 1.1 g; fat 11.0 ± 1.0 g) consumed in the daytime (1000 h) or nighttime (2300 h) for 13 days in
healthy, normal weight women (n = 11, age, 23 ± 1 years, BMI 20.6 ± 2.6 kg/m2). It was reported that
despite no difference in nutrient composition or calorie intake for each 13 day period, the nighttime
eating resulted in small decreases in 24 h fat oxidation and small increases in total cholesterol [51]. The
short duration of this study does not allow for conclusions to be drawn with regard to body composition
changes, however, body weight was unchanged. Nevertheless, as there is typically a long duration
between eating dinner, sleep, and the next main meal (i.e., breakfast the following morning), the
overnight period may represent a 6–8 h window of opportunity to potentially optimize health,
metabolism and overall human performance. Fortunately, short-term preliminary studies have provided
insight to the potential benefits of pre-sleep nutrient intake and its relevance to healthy, active
young [47,52] and older individuals [45] and diseased populations [46,48–50,53,54] (Table 1).
3.1. Young, Active Individuals
It is well known that acute improvements in muscle protein synthesis, glycogen resynthesis, anabolic
hormones, and performance outcomes are optimized when nutrients are consumed in close proximity to
exercise (i.e., before, during, or immediately after exercise) [55–58] rather than delaying intake for hours
before and after exercise [59,60]. Of interest, but lacking scientific support, is whether the consumption
of nutrients prior to sleep has the potential to augment physiological adaptations and outcomes, perhaps
when combined with traditional nutrient timing strategies. The benefits of a nocturnal supply of nutrients
during the overnight period may have a pivotal role in sport and performance nutrition as active
individuals, athletes, and fitness enthusiasts alike are constantly looking for ways to maximize
physiological adaptations, achieve optimal body composition, and improve performance.
Protein intake prior to sleep is commonplace among active individuals but until now, evidence-based
outcomes from this practice were nonexistent [47,52]. Res et al. [52] was the first to investigate whether
casein protein consumed before sleep could improve post-exercise recovery. Following a full day of
dietary standardization, sixteen recreationally active males performed a single 45 min bout of resistance
type exercise in the evening (2000 h). Immediately following exercise all participants were given
identical post-exercise beverages (60 g carbohydrate, 20 g whey protein). Approximately 30 min before
sleep (~2.5 h post-exercise) participants received either 40 g of casein protein (160 kcals; intrinsically
L-[1-13C]phenylalanine-labeled casein obtained from Holstein cow infusion) or a non-caloric placebo
beverage. Compared to the placebo group, those receiving the casein before sleep had higher plasma
essential amino acid concentrations indicating that protein ingestion before sleep was effectively
digested and absorbed. The increase in amino acid availability translated to higher whole-body and
muscle protein synthesis rates (~22%, Figure 1A) and a net positive protein balance during the overnight
period in the group receiving protein compared to the placebo control [52].
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Table 1. Effects of small meals/snack consumed at night.
Author
Design
Subjects
Food/Macronutrient
Outcome
Waller et al. [46] Consume cereal with 2/3 cup of fat-free milk at
least 90 min post-dinner vs. or no-cereal for
4 weeks
Overweight and
obese adults Cereal (100135 kcals) with low
fat milk (~60 kcals)
↓ Body weight
(0.84 ± 1.61 kg)
Groen et al. [45] Single dose of CAS during sleep via nasogastric
tube Elderly men 40g CAS (160 kcals)
↑ Muscle protein synthesis
↓ Hunger (the following
morning)
Res et al. [52] Acute resistance exercise bout (20002100 h)
followed by single dose of CAS 2.5 h post exercise
(2330 h) and then sleep (2400 h)
Recreationally
active men 40g CAS (160 kcals) ↑ Muscle protein synthesis
Hibi et al. [51] Consume a snack during the day (1000 h) or night
(2300 h) for 13 days
Normal weight
women
200 kcal snack
(20g CHO, 3 g protein, 11g fat)
↓24 h fat oxidation
↑ Total & LDL cholesterol
Madzima et al. [47] Single dose of WH, CAS, CHO or Placebo
consumed 30 min before bed Physically active
men
CHO (33 g, 150 kcals)
WH (30 g, 150 kcals)
CAS (30 g,140 kcals)
Placebo (0 kcals)
↑ Morning metabolism with
CHO, WH, CAS
Kinsey et al. [48] Single dose of WH, CAS, CHO consumed 30 min
before bed Overweight and
obese women
CHO (33 g, 150 kcals)
WH (30 g, 150 kcals)
CAS (30 g,140 kcals)
↑ Morning insulin in all
groups
↓ Hunger (the following
morning)
Figueroa et al. [50] Single dose of WH, CAS, CHO consumed 30 min
before bed and exercise
training for 4 weeks
Obese women CHO (33 g, 150 kcals)
WH (30 g, 150 kcals)
CAS (30 g,140 kcals)
↓ Blood pressure
↓ Arterial stiffness
Ormsbee et al. [49] Single dose of WH, CAS, CHO consumed 30 min
before bed and exercise
training for 4 weeks
Overweight and
obese women
CHO (33 g, 150 kcals)
WH (30 g, 150 kcals)
CAS (30 g,140 kcals)
↑ Morning satiety with CAS
Greater magnitude of ↓ body
fat and fat mass with WH
(non-significant)
Notes: WH, whey protein; CAS, casein protein; CHO, carbohydrate; ↑ , increase; ↓ decrease; all studies were randomized, controlled, trials.
Nutrients 2015, 7 2653
Casein protein has been suggested to be best before sleep as it is a slow-release protein [61] and may
prolong the anabolic milieu, however, the lack of available data comparing the effect of different
macronutrients and proteins consumed before sleep limits the ability to draw specific conclusions.
Recent work from Madzima et al. [47] were the first to compare different macronutrients (carbohydrate
vs. protein) and proteins (casein vs. whey) to a non-caloric placebo consumed prior to sleep on
next-morning satiety and metabolism, independent of an exercise stimulus, in healthy, physically active
young men. This study had a randomized, double blind, crossover design with treatments separated by
48–72 h. Supplements were provided in beverage form at ingested at least two hours after dinner but
within 30 min of going to bed. The authors reported no differences between casein (140 kcal; 30 g
micellar casein, 3 g carbohydrate, 0.5 g fat), whey (150 kcal; 30 g whey protein with a 50% blend of
whey protein isolate and concentrate, 4 g carbohydrate and 1.5 g fat), or carbohydrate (150 kcal; 0 g
protein, 34 g maltodextrin and 2 g fat) in satiety or metabolism. Interestingly, it was reported that
consuming a caloric beverage prior to sleep, regardless of type, increased resting energy expenditure,
measured the following morning, compared to a non-caloric beverage (Figure 2) [47].
The role of pre-sleep nutrition in active individuals is a largely unexplored area and available data are
limited. However, taken together, the data suggest that it may be advantageous for active individuals to
consume a small, nutrient dense, high protein beverage (~150 kcals) before bed [47,52]. It is plausible
to hypothesize that acute enhancements in overnight muscle protein synthesis and next morning resting
metabolism may further aid in the maintenance of and/or improvement in body composition and thereby
provide a competitive advantage in healthy, physically active individuals. While this is exciting, data
does not exist to support or refute these ideas. However, it is clear that longer-term studies are warranted
to see if meaningful differences exist over time in terms of exercise adaptations and performance or
recovery outcomes (i.e., strength or time trial performance, glycogen resynthesis, muscle damage, and
inflammation). Furthermore, when training or competition occurs late in the evening (e.g., many
recreational sports and clubs) or early in the morning following an overnight fast (e.g., endurance
events), the potential benefits of pre-sleep nutrition are evident.
Figure 1. Overnight Mixed Muscle Protein Synthesis in Younger (A) and Older Men (B).
PLA, placebo; PRO, protein. This figure was adapted and redrawn from Res et al. [52] and
Groen et al. [45]. These studies determined mixed muscle protein fractional synthetic rate
using L-[ring-2H5]phenylalanine enrichment as a precursor. * indicates significant difference
from PLA.
Nutrients 2015, 7 2654
Figure 2. Resting Energy Expenditure Following Nighttime Macronutrient Ingestion in
Young Active Men. PLA, placebo; CHO, carbohydrate; WH, whey protein; CAS, casein
protein. This figure was adapted and redrawn from Madzima et al. [47]. * indicates
significant difference from CHO, WH, and CAS.
3.2. Older Individuals
In today’s society people are living longer and the older population continues to grow at an alarming
rate. In addition, older individuals have an increased risk of developing sarcopenia, the progressive loss
of muscle mass and strength that increases the risk for physical disability, poor quality of life and reduced
physical performance [62]. As aging and life expectancy are on the rise, multifactorial strategies aimed
at attenuating sarcopenia to maintain functionality and quality of life are essential. Providing nutrients
in close proximity to or during sleep to maintain and/or attenuate the loss of muscle mass may be a novel
nutrition concept worthy of exploration.
To date, there is only one study that examined whether protein provided during sleep is properly
digested and absorbed, and can subsequently improve overnight muscle protein synthesis in sixteen
elderly men [45]. Due to the presence of a circadian variation in gastric emptying [2], it was speculated
that providing nutrients at this time may not be efficiently utilized. Groen et al. administered 40 g of
casein protein (intrinsically L-[1-13C]phenylalanine-labeled casein) through a nasogastric tube during
sleep (0200–0205 h) and simultaneously assessed dietary protein digestion and absorption kinetics and
muscle protein synthesis during overnight sleep in vivo. Consistent with findings in recreationally active
men [52], this study reported that protein administration during sleep was well digested and absorbed
and concomitantly promoted overnight muscle protein accretion in elderly men (Figure 1B) [45]. This
find is interesting and highlights the potential significance of pre-sleep protein intake in populations
susceptible to muscle loss and wasting (e.g., aging, cancer cachexia).
3.3. Obesity and Other Diseases
3.3.1. Obesity
Given the growing interest in nighttime eating and its potential link to obesity and other
cardiometabolic diseases, it is important to examine the impact of nighttime macronutrient choices on
health outcomes in these populations. Waller et al. [46] demonstrated that providing a low fat, low
calorie nighttime snack as opposed to the typical high fat/high calorie food option may be beneficial to
Nutrients 2015, 7 2655
overweight and obese adults. In this four week study, overweight and obese adults (n = 58; age,
18–65 years) were randomized to receive a structured, post-dinner snack consisting of cereal (1 cup of
ready-to-eat cereal containing 100135 kcals, 23–32 g carbohydrates, 26 g protein, <0.5g fat, and
1–1.5 g fiber) and 2/3 cup of low-fat milk (~60 kcals) or a control group that maintained their normal eating
and post-dinner snacking behaviors (average snacking = 6.19 ±1.58 evenings per week, mean ± SD).
The cereal was consumed every night at least 90 min after dinner for the duration of the study and the
control group was offered the cereal after the initial four weeks. Findings from this study indicated that
having a structured, post-dinner snack resulted in lower total daily caloric intake, evening caloric intake
and modest weight loss (0.84 ± 1.61 kg) in compliant individuals [46]. While not explicitly described,
an interesting theory is that less food was consumed at dinner when it was known that an evening snack
would be available.
In an acute study, Kinsey et al. [48] investigated the effect of different macronutrients (carbohydrate
vs. protein) and proteins (casein vs. whey) consumed at night before sleep on next morning appetite and
cardiometabolic risk in sedentary overweight and obese women. The single-macronutrient beverages
(casein vs. whey vs. carbohydrate; 140–150 kcals) and supplementation protocol (two hours post-dinner
but within 30 min of sleep) in this study were identical to those used by Madzima et al. [47]. This study
revealed that these nighttime macronutrient beverages, regardless of type, lead to greater subjective
satiety and less desire to eat. However, regardless of consumption of protein-only or carbohydrate-only,
a small but significant increases in insulin levels and subsequent insulin resistance, as calculated using
the homeostatic model of insulin resistance, was observed the morning following nighttime feeding [48].
The latter finding suggests that nighttime ingestion of protein or carbohydrate before sleep may elicit
unfavorable metabolic effects in sedentary overweight and obese women. However, it was speculated
that longer-duration interventions that combine pre-sleep nutrient intake with daily exercise may
ameliorate this effect.
Interestingly, two recent studies [49,50] were designed to test the additive effect of four weeks of
exercise training (3×/week; 2 days of resistance training and 1 day of high intensity cardiovascular
interval training) and nighttime macronutrient ingestion (every night; beverages identical to those used
by Madzima et al. [47] and Kinsey et al. [48]) on various health and performance outcomes.
Ormsbee et al. [49] examined the additive effects of nighttime consumption of whey, casein or a
carbohydrate beverage on appetite, cardiometabolic health and muscular strength in overweight and
obese women (body mass index range: 25.7–47.5 kg/m2). As a result of exercise training, all groups
showed modest, albeit significant, increases in muscle strength and lean mass, and decreased body fat
(as measured by dual energy X-ray absorptiometry). Regarding appetite changes, greater morning satiety
was reported in the group consuming casein at night compared to those consuming whey or
carbohydrate. More importantly, the increase in morning insulin levels and insulin resistance observed
acutely by Kinsey et al. [48] in response to nighttime protein and carbohydrate intake was abolished
when exercise training was added to nighttime feeding in obese women [49]. Interestingly, although not
statistically significant, it is noteworthy to mention that both acutely [48] and after four weeks [49] the
direction of change for next morning metabolism was positive for the groups ingesting protein before
sleep and negative for those ingesting carbohydrates (Figure 3). Considering that a higher protein diet
has been shown to attenuate the typical drop in metabolism during sleep in overweight and obese adults,
as compared to diets higher in carbohydrate and fat [63], these changes may have physiological relevance.
Nutrients 2015, 7 2656
Figure 3. Resting Metabolic Rate (percent changes) Following Acute (A) and Four Weeks
(B) of Nighttime Macronutrient Ingestion in Overweight and Obese Women. CHO,
carbohydrate; WH, whey protein; CAS, casein protein. This figure was adapted and redrawn
from Kinsey et al. [48] and Ormsbee et al. [49].
Moreover, Figueroa et al. [50] examined the impact of nighttime ingestion of whey or casein protein
on blood pressure, and arterial function in young obese women with high blood pressure compared to a
carbohydrate control group. This study demonstrated that the combination of nighttime protein
supplementation and exercise training reduced both aortic systolic blood pressure, arterial stiffness (as
measured by pulse wave velocity), and augmentation index compared to baseline and the
carbohydrate beverage.
Overall, it appears that when exercise is combined with nighttime feeding of small, protein-rich
nutrient intake before sleep, some positive physiological adaptations may occur in obese women.
The benefit for other clinical populations, however, deserves some consideration.
3.3.2. Glycogen Storage Disease and Diabetes
Patients with certain glycogen storage diseases (GSD) and those with Type 1 Diabetes (T1DM) are
susceptible to nocturnal hypoglycemia and bedtime nutrient delivery provides an avenue for a supply of
glucose during the night. GSDs are a group of genetic disorders that result from defects in enzymes
required for glycogen synthesis or degradation [64]. Type I GSD is characterized by a deficiency in
glucose-6 phosphatase activity, the liver enzyme required to dephosphorylate glucose to help maintain
blood glucose levels. During the overnight period (i.e., an extended fasting period) the liver is primarily
responsible for maintaining blood glucose levels, however, the metabolic defect associated with Type 1
GSD impairs glycemic regulation. Accordingly, treatments for this condition are aimed at dietary
regimens that provide a constant supply of glucose throughout the day and night to prevent
hypoglycemia [64]. Studies have shown that individuals with Type I GSD can benefit from nighttime
nutrient availability [53,65,66]. Traditional practice has been to provide uncooked cornstarch, a slow digesting
Nutrients 2015, 7 2657
carbohydrate and an effective source of continuous glucose for the prevention of hypoglycemia [67],
at various intervals (2–5 h) throughout the day with nightly doses being administered by nasogastric
feeding [66] or by interrupting sleep and waking the individual to eat [53]. The latter option is not ideal
but, unfortunately, is most applicable and cost-effective in free-living adults with this condition. Thus,
the efficacy of a pre-sleep option capable of sustaining blood glucose levels during sleep and hence
prevent nocturnal hypoglycemia is immense. Wolfsdorf et al. [53] compared the effects of providing
isoenergetic amounts of uncooked cornstarch orally on consecutive nights as single dose at bedtime or
as two equally divided doses given at bedtime and mid-sleep in young adults with Type 1 GSD.
The results demonstrated that blood glucose concentrations were maintained for 7 h and 9 h with the
single and divided dose respectively. This highlights the feasibility of a bedtime dose of nutrients to aid
in the maintenance of blood glucose concentrations during sleep in patients with Type 1 GSD.
T1DM is characterized by a defect in insulin production as a result of pancreatic beta cell destruction
and, as a result, these individuals must rely on exogenous insulin in order to maintain appropriate blood
glucose levels. Similar to those with Type 1 GSD, nocturnal hypoglycemia is also a concern for T1DM
patients, particularly when bedtime glucose concentrations are ≤180 mg/dL (≤10 mmol/L) [54].
Likewise, bedtime feedings of cornstarch and/or protein have been useful in reducing hypoglycemic
occurrences in populations with T1DM [54,68–70]. Kalergis et al. [54] examined the effect of bedtime
ingestion of a standard snack (191 kcals, two starch and one protein exchange according the Academy
of Nutrition and Dietetics), cornstarch snack (187 kcals), protein-rich snack (192 kcals), and no snack
(0 kcals, aspartame-containing drink) on nocturnal hypoglycemia in patients with T1DM undergoing
intensive insulin management. In this study, both the standard and protein-rich snacks were most
successful at preventing nocturnal hypoglycemia while the no snack treatment had the greatest
hypoglycemic episodes. However, although not significant, the incidence of next morning
hyperglycemia in response to these nighttime snacks was greatest for the protein snack (33%), followed
by the standard (29%) and cornstarch snack (29%), with the no snack treatment being the lowest (8%).
It can be speculated that increased glucagon secretion and decreased insulin levels in the morning may
have contributed the glycemia in this population [70]. Overall, this indicates that proper snack
composition and individual variability may need to be considered when determining appropriate bedtime
snacks for some clinical populations.
4. Conclusions
Old perspectives for nighttime eating have been primarily based on populations of shift workers, night
eating syndrome patients, and epidemiological data and suggest that the consumption of large mixed
meals combined with irregular sleep patterns increase susceptibility to weight gain, obesity, and
cardiometabolic diseases. In recent years, data from healthy men has shown that consuming small
~150 kcal protein-rich beverages appears to improve overnight muscle protein synthesis, morning
metabolism and satiety. However, the impact in healthy women has not been studied yet. In obese
women, eating before sleep has been shown to improve morning appetite but also increase insulin
resistance. However, the addition of exercise training for four weeks appears to eliminate any adverse
effects of nighttime feeding in this population and has been shown to improve some indicators of
cardiovascular health. In other diseased populations (e.g., GSD, T1DM), eating before bed is actually
Nutrients 2015, 7 2658
required for survival. However, management with individually tailored nighttime feeding protocols may
optimize their clinical outcomes. Clearly, more research is required to examine this new perspective of
nighttime feeding (small, nutrient dense, snacks before sleep) as it relates to sedentary individuals,
athletes, and clinical populations. Moreover, identifying the role of nighttime feeding in recovery from
exercise and improving performance, if any exist, are warranted along with identifying the overnight
metabolic changes that may occur from nighttime feeding (i.e., fat metabolism).
Acknowledgments
The authors would like to thank the Florida State University Libraries Open Access Publishing Fund
for covering the publication fees for this manuscript.
Author Contributions
A.W.K. and M.J.O. conceived, designed and drafted the manuscript. All authors read and approved
the final manuscript.
Conflicts of Interest
The authors declare no conflict of interest.
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... In 16 healthy individuals (8 females (22.2 ± 2.6 yrs) and 8 males (22.8 ± 3.5 yrs)), exposure to bright light (>500 lux) in the evening and while asleep significantly increased plasma glucose and insulin levels compared to dim light exposure (<5 lux), implicating glucose intolerance and insulin insensitivity [97]. For night shift workers and individuals with night eating syndrome, a large portion of total energy intake occurs after dinner, which may contribute to health consequences [98]. Preference for certain types of food and dietary intake among shift workers has been examined in simulated and free-living conditions. ...
... Additionally, the general view of restricting food intake before sleep has been challenged due to new perspectives on food intake at night. One study has reported that small amounts of protein-rich beverages demonstrated a positive impact on muscle protein synthesis at nighttime in healthy men [98]; thus, food intake at night may contribute positively to metabolism depending on the amount and composition of the food consumed. Understanding the effect of the food composition and the amount consumed may provide ways to minimize metabolic consequences when food consumption is inevitable at nighttime. ...
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... Previous studies have mainly focused on the effect of nighttime snacking on the physiological functions of older adults. Results showed that eating a small amount of nutrient-dense but low-energy food before sleep could promote older adults' physical health [7,9,10]. More specifically, studies have suggested that appropriate nighttime snacking compensates for anabolic resistance and benefits protein synthesis and cardiometabolic health [10][11][12][13]. ...
... The amount of energy intake is a crucial factor. Previous studies have demonstrated that a small amount (~150 kcal) of a single nutrient or mixed diet before sleep is not harmful but advantageous to physical and mental health [9]. In addition, a 4-week intervention study on sedentary obese female showed that ingesting~150 kcal of whey, casein, or carbohydrates before sleep (at least 2 h after dinner) combined with physical exercise not only reduced body fat, optimized body structure, and strength but also improved the emotional status in intervention groups [41]. ...
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... Furthermore, eating fewer meals may be associated with eating out and at late hours, which can be characterized by energyrich foods with low nutrient density such as fried foods, alcohol consumption and lower amounts of foods with high nutrient density such as fruits and vegetables (Misan et al., 2019;Aljuraiban et al., 2014). Therefore, positive results have been observed when foods eaten late are small in amount, rich in nutrients and low in energy and/or macronutrients (Kinsey & Ormsbee, 2015). In addition, changes in meal frequency and timing have the potential to influence energy and macronutrient intake (Englund-Ögge et al., 2017;Paoli et al., 2019). ...
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... Additionally, it has been reported that late eating, which refers to delay in the timing of meals (commonly the main meal of the day or the dinner) may increase the risk for developing cardiometabolic diseases [279]. In fact, late eating was associated with abdominal obesity, inflammatory RCT randomized controlled trial, NS no significant, T2DM type 2 diabetes mellitus, NAFLD non-alcoholic fatty liver disease, PCOS polycystic ovary syndrome, MDA malondialdehyde, NF-kB transcription nuclear factor kappa B, CRP C-reactive protein, IL-6 interleukin 6, TNF-α tumor necrosis factor alpha, IL-8 interleukin 8, IL-4 interleukin 4, IL-10 interleukin 10, SIRT1 sirtuin 1, ESR erythrocyte sedimentation rate, oxLDL oxidized LDL, LDH lactate dehydrogenase biomarkers such as IL-6 and CRP, and circadian-related disturbances in children [280]. ...
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... Thus, adherence to the protocol was verified regarding similar presleep macronutrient ingestion, and its influence on baseline blood flow measured by CEUS is unknown so far. However, presleep macronutrient ingestion has been shown to alter morning metabolism and muscle protein synthesis [47,48], thereby harboring a risk of inconsistently affecting muscle perfusion [49]. ...
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... However, strict restriction of nocturnal eating can also result in undue psychological stress and similarly lead to preterm birth [44]. As such, pregnant women might consider eating a small amount of food that is low in calories and rich in protein [45], serotonin, and folate, such as kiwifruit [46], or foods that contain melatonin, such as eggs, fish, nuts, and mushrooms [47], to address their physical needs while not compromising their sleep quality. Nevertheless, it is worth noting the potential presence of reverse causality, where poor sleep might contribute to nocturnal eating. ...
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... Eating before bed time has long been controversial [46,47], but for the RT population aimed at muscle gaining, they preferred ingesting protein before bedtime, which has been identified as advantageous to MPS and muscle recovery in both acute and long-term studies among both adults and older adults [48][49][50]. Antonio et al. (2017) [9] conducted an 8-week intervention in healthy males to compare the effects of consuming protein (casein, 54 g per serving) in the morning before noon versus consuming protein~90 min prior to sleep. This study found that the lean tissue mass of subjects in morning group increased by 0.4 kg, and the evening group increased by 1.2 kg despite no significant difference between groups, suggesting that supplementing casein before sleep could better stimulate MPS, which was also supported by data from Burk et al. [51]. ...
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To investigate associations between shiftwork and glomerular filtration rate among white/Hispanic (n = 273) and African American (n = 81) police officers. Analysis of variance/analysis of variance was utilized to compare mean values of estimated glomerular filtration rate (eGFR) across shiftwork categories. Shiftwork was significantly associated with eGFR among white/Hispanic officers only: day (88.6 ± 2.8), afternoon (90.6 ± 2.9), and night shift (83.1 ± 3.1 mL/min/1.73 m); afternoon versus night, P = 0.007. Percentage of hours worked on the night shift was inversely associated with mean levels of eGFR, trend P = 0.001. Body mass index modified the association between shiftwork and eGFR (interaction P = 0.038). Among officers with body mass index 25 kg/m or higher, those who worked the night shift had the lowest mean eGFR (afternoon vs night, P = 0.012; day vs night, P = 0.029). Night-shift work was associated with decreased kidney function among white/Hispanic officers. Longitudinal studies are warranted among all races.
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