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Intense meditation practices help to achieve a harmony between body and mind. Meditation practices influence brain functions, induce various intrinsic neural plasticity events, modulate autonomic, metabolic, endocrine, and immune functions and thus mediate global regulatory changes in various behavioral states including sleep. This brief review focuses on the effect of meditation as a self regulatory phenomenon on sleep.
published: 18 April 2012
doi: 10.3389/fneur.2012.00054
Meditation and its regulatory role on sleep
Ravindra P. Nagendra, Nirmala Maruthai and Bindu M. Kutty*
Department of Neurophysiology, National Institute of Mental Health and Neurosciences, Bangalore, India
Edited by:
V. Mohan Kumar, Sree ChitraTirunal
Institute for Medical Sciences and
Technology, India
Reviewed by:
Sunao Uchida, Waseda University,
V. Mohan Kumar, Sree ChitraTirunal
Institute for Medical Sciences and
Technology, India
Bindu M. Kutty, Department of
Neurophysiology, National Institute of
Mental Health and Neurosciences,
Bangalore 560029, India.
Intense meditation practices help to achieve a harmony between body and mind. Medi-
tation practices influence brain functions, induce various intrinsic neural plasticity events,
modulate autonomic, metabolic, endocrine, and immune functions and thus mediate global
regulatory changes in various behavioral states including sleep. This brief review focuses
on the effect of meditation as a self regulatory phenomenon on sleep.
Keywords: meditation, sleep, brain functions, autonomic activity, endocrine functions, neural plasticity
Meditation practices have been a life style practiced in India thou-
sands of years ago. Proficient meditative practices help to integrate
the brain functions, regulate various physiological mechanisms
resulting in a state of mental and physical well being. Studies
of long term transcendental meditation (TM) practitioners have
shown that TM helped to achieve a state of “restful alertness” a
state of deep physiological rest which was associated with periods
of respiratory suspension without compensatory hyper ventilation,
decreased heart rate, heightened galvanic skin response along with
enhanced wakefulness (Wallace, 1970). This restful alertness and
hypometabolic state were believed to be the outcome of physi-
ological and biochemical changes brought about by meditation
practices (Young and Taylor, 1998).
The effect of meditation on sleep was first reported by Mason et al.
(1997) in practitioners of TM. The main objective was to evaluate
the neurophysiological correlates of the higher states of conscious-
ness during sleep. The study reported that the senior meditators
spent more time in the slow wave sleep (SWS) with higher theta–
alpha power with background delta activity,together with reduced
electromyogram (EMG). The rapid eye movement (REM) sleep
was also found to be enhanced. The distinct theta–alpha pattern
observed during sleep was considered as an electrophysiological
correlate of a stabilized state of higher consciousness in sleep. Fur-
ther, the study opened up new avenues to explore the influence of
meditation on sleep.
Studies by Sulekha et al. (2006) and Ravindra et al. (2010)
demonstrated the differences in sleep architecture in practi-
tioners of Vipassana meditation (mindfulness meditation). The
sleep architecture of senior practitioners of Vipassana medita-
tion was endowed with enhanced states of SWS and REM sleep
compared to that of non-meditating control group. Vipassana
meditators showed 17.95, 11.3, and 10.63% of SWS among
younger (30–39 years), middle (40–49 years), and older (50–
60 years) age groups respectively. On the other hand, the corre-
sponding non-meditating controls showed a significant reduction
of SWS with increasing age, i.e., 11.29, 6.65, and 3.94%. Vipas-
sana meditators from all age groups showed more number of
sleep cycles, indicating quality sleep. The study suggested that
the older meditators could retain the sleep pattern of younger
non-meditating controls. Aging is known to reduce the activity of
the slow wave resonating mechanism either by actual loss of neu-
rons or reduced activation of thalamo-cortical pathways (Feinberg
et al., 1967;Mourtazaev et al., 1995) and also by reduced spin-
dle generation during NREM sleep stage 2 (Nicolas et al., 2001).
Vipassana meditation appears to preserve the SWS,suggesting that
meditation could prevent the age associated changes in the slow
wave generating mechanisms.Vipassana meditation also enhanced
the REM sleep states. Meditation practices are reported to enhance
the amplitude of gamma synchrony, strengthen the thalamo-
cortical and cortico-cortical interactions (Lutz et al., 2004). These
mechanisms brought about stronger network synchronization and
altered the neural structure and functions (Lazar et al., 2005;
Pagnoni and Cekic, 2007). Based on the above observations, the
changes in sleep architecture in the Vipassana meditation practi-
tioners could be attributed to the neural plasticity events associated
with meditation.
Changes in autonomic activity had been reported with respect
to specific sleep states with predominant parasympathetic activ-
ity in SWS and sympathetic activity during REM sleep (Pivik
et al., 1996;Otzenberger et al., 1997;Trinder et al., 2001;Pede-
monte et al., 2005). Such sleep state dependent autonomic changes
maintain the homeostasis during sleep. Aging alters autonomic
flexibility leading to an overall increase in sympathetic activity
along with reduced parasympathetic activity, thereby bringing
about autonomic arousal and decrease in sleep quality. Reduced April 2012 | Volume 3 | Article 54 | 1
Nagendra et al. Meditation and sleep
parasympathetic activity along with inefficient baroreflex mecha-
nisms during REM sleep have been reported to cause unfavorable
cardiac events (Somers et al., 1993;Ramaekers et al., 1999;Jones
et al., 2003). Meditation practices help to bring about sympatho-
vagal balance with parasympathetic predominance among experi-
enced meditators and also in novice meditators with less practice
(Wu and Lo, 2008;Zeidan et al., 2010). Vipassana meditation prac-
tices help to retain the flexibility of autonomic activity during
different stages of sleep. Further, heart rate variability evalua-
tion during REM sleep showed higher sympathetic activity in
meditators than in controls. This higher sympathetic activity in
meditators was effectively buffered by parasympathetic activity
unlike the non-meditating controls (unpublished data). These
studies have demonstrated a greater insight into the modula-
tory effect of meditation practices on autonomic functions during
sleep. Meditation practices are associated with enhanced frontal
midline theta activity (Aftanas and Golocheikine, 2001;Travis and
Shear, 2010). The frontal midline theta activity originates from the
anterior cingulate cortex and controls the parasympathetic activ-
ity (Tang et al., 2009). Vipassana meditation practices would have
activated the anterior cingulate cortex and hence modulated the
parasympathetic activity during sleep. These reports are sugges-
tive of a positive modulatory role of meditation in sleep through
autonomic functions.
Meditation practices were reported to regulate the hypothalamo
pituitary adrenal (HPA) Axis and thereby the cortisol and cat-
echolamine levels (Jevning et al., 1978a;Infante et al., 2001).
Further,meditation techniques were also known to increase dehy-
droepiandrosterone (Glaser et al., 1992), anterior Pituitary hor-
mones like growth hormone, thyroid stimulating hormone (TSH),
prolactin (Jevning et al., 1978b;Werner et al.,1986;MacLean et al.,
1997), and melatonin levels (Massion et al., 1995;Tooley et al.,
Melatonin plays a vital role in the physiological regulation of
sleep in both blind and normal individuals (Pandi-Perumal et al.,
2006). Melatonin rhythm follows a raising and falling phase with
corresponding alterations in sleep propensity (Dijk and Cajochen,
1997;Dijk et al., 1997). Melatonin exerts its hypnotic effect by
acute inhibition of suprachiasmatic nucleus (von Gall et al., 2002)
and also by facilitating hypothermic response through peripheral
vasodilatation (Krauchi et al., 1997). Melatonin is widely used in
the management of sleep rhythm disorders due to jetlag, shift-
work, and insomnia (Martinez and Lenz, 2010). In addition to its
role in sleep, melatonin acts as an antioxidant and immunomod-
ulator (Maestroni, 2001), oncostatic, antiaging agent, and helps in
bringing sense of wellbeing (Armstrong and Redman, 1991;Reiter,
1995;Maestroni, 2001;Guerrero and Reiter, 2002;Pandi-Perumal
et al., 2006). Aging attenuates the melatonin secretion (Sack et al.,
1986) and hence affect the sleep quality in aged population.
Meditation practices are reported to enhance the melatonin
levels (Tooley et al., 2000), the precursors of melatonin espe-
cially the serotonin (Bujatti and Riederer, 1976) and noradren-
alin (Lang et al., 1979). Meditation increases melatonin concen-
tration by slowing its hepatic metabolism or augmenting the
synthesis in the pineal gland (Massion et al., 1995). Diurnal
melatonin levels were found to be significantly high in Vipassana
meditators (approximately 300pg ml) than non-meditating con-
trols (65 pg ml; unpublished data). By considering the role of mela-
tonin in sleep maintenance, it might be concluded that meditation
practices enhance melatonin levels and hence quality of sleep.
Sleep is reported to be associated with reduced heart rate, blood
pressure, respiratory rate, and rhythm, oxygen consumption, anx-
iety or arousal, and an overall decrease in basal metabolic levels
leading to a hypometabolic state. This phenomenon of sleep
induced hypometabolic state is a natural and spontaneous out-
come necessary for biological survival (Young and Taylor, 1998).
Imaging studies have shown that during NREM sleep the blood
flow to areas associated with executive functions such as frontal
and parietal cortex, thalamus, basal ganglia, and cerebellum has
been reduced and bringing about the feeling of hypnogogic effect
during sleep (Kajimura et al., 1999;Kjaer et al., 2002).
Meditation also brings a sustained hypometabolic state termed
as relaxation response by Herbert Benson and helps in sleep initia-
tion (Wallace et al., 1971). Similarly,meditation techniques help to
regulate the blood flow to the executive regions of the brain dur-
ing sleep (Lou et al., 1999). Meditation practices down regulate
HPA axis reducing the stress, prolactin, TSH levels (Jevning et al.,
1978a); bring about alterations in the intermediary metabolism
favoring an anabolic state. Thus, meditation helps to maintain a
wakeful hypometabolic state with parasympathetic predominance
(Young and Taylor, 1998). Both the state and trait characteristics of
meditation practices provide an advantage that it continually resets
the metabolic functioning despite varying levels of stress. This
internal metabolic resetting form the baseline trait characteristics
necessary for all potential changes brought about by meditation
practices. Further, meditative practices beneficially influence the
cognitive, emotional, and behavioral aspects. Thus meditation is
shown to have a greater potential to influence many physiological
and behavioral states including sleep (Carlson et al., 2007;Ong
et al., 2008;Sibinga et al., 2011).
It has been hypothesized that meditation practices activate
prefrontal cortex, fronto-limbic, fronto-parietal neural networks
and limbic and paralimbic cortices associated with sympathetic
arousal. Meditation practices activate structures like insula, ante-
rior cingulate, and hypothalamus and bring about autonomic and
humoral changes (Newberg and Iversen, 2003). Meditation thus
produces a continuum of global regulatory changes at various
behavioral levels favoring quality sleep.
It is evident from the literature cited that practice of medita-
tion brings about global changes. Many of these alterations in
physiological functions have great similarities to the changes that
are happening during sleep. It has been proposed that sleep is
an autoregulatory global phenomenon (Kumar, 2010). It is also
true that meditation influences sleep and its functions. It appears
that various components of sleep generating mechanisms can be
altered with meditation. Meditation, with its global effects on body
and brain functions helps to establish a body and mind harmony.
Thus meditation practices as an autoregulatory integrated global
phenomenon, opens a wider scope for understanding the unique
aspects of human sleep and consciousness.
Frontiers in Neurology | Sleep and Chronobiology April 2012 | Volume 3 | Article 54 | 2
Nagendra et al. Meditation and sleep
Aftanas, L. I., and Golocheikine, S. A.
(2001). Human anterior and frontal
midline theta and lower alpha reflect
emotionally positive state and inter-
nalized attention: high-resolution
EEG investigation of meditation.
Neurosci. Lett. 310, 57–60.
Armstrong, S. M., and Redman, J.
R. (1991). Melatonin: a chronobi-
otic with anti-aging properties? Med.
Hypotheses 34, 300–309.
Bujatti, M., and Riederer, P. (1976).
Serotonin, noradrenaline, dopamine
metabolites in transcendental
meditation-technique. J. Neural
Transm. 39, 257–267.
Carlson, L. E., Speca, M., Faris, P.,
and Patel, K. D. (2007). One year
pre-post intervention follow-up of
psychological, immune, endocrine
and blood pressure outcomes of
mindfulness-based stress reduction
(MBSR) in breast and prostate
cancer outpatients. Brain Behav.
Immun. 21, 1038–1049.
Dijk, D. J., and Cajochen, C. (1997).
Melatonin and the circadian regu-
lation of sleep initiation, consolida-
tion, structure, and the sleep EEG. J.
Biol. Rhythms 12, 627–635.
Dijk, D. J., Shanahan, T. L., Duffy,
J. F., Ronda, J. M., and Czeisler,
C. A. (1997). Variation of elec-
troencephalographic activity during
non-rapid eye movement and rapid
eye movement sleep with phase
of circadian melatonin rhythm in
humans. J. Physiol. (Lond.) 505(Pt
3), 851–858.
Feinberg, I., Koresko, R. L., and Heller,
N. (1967). EEG sleep patterns as a
function of normal and pathologi-
cal aging in man. J. Psychiatr. Res. 5,
Glaser, J. L., Brind, J. L., Vogelman, J.
H., Eisner, M. J., Dillbeck, M. C.,
Wallace, R. K.,Chopr a,D., and Oren-
treich, N. (1992). Elevated serum
dehydroepiandrosterone sulfate lev-
els in practitioners of the transcen-
dental meditation (TM) and TM-
Sidhi programs. J. Behav. Med. 15,
Guerrero, J. M., and Reiter, R. J. (2002).
Melatonin-immune system relation-
ships. Curr. Top. Med. Chem. 2,
Infante, J. R., Torres-Avisbal, M., Pinel,
P., Vallejo, J. A., Peran, F., Gonza-
lez, F., Contreras, P., Pacheco, C.,
Roldan, A., and Latre, J. M. (2001).
Catecholamine levels in practition-
ers of the transcendental medita-
tion technique. Physiol. Behav. 72,
Jevning, R., Wilson, A. F., and Smith,
W. R. (1978a). The transcendental
meditation technique, adrenocorti-
cal activity, and implications for
stress. Experientia 34, 618–619.
Jevning, R., Wilson, A. F., and Vander-
Laan, E. F. (1978b). Plasma prolactin
and growth hormone during medi-
tation. Psychosom. Med. 40,329–333.
Jones, P. P., Christou, D. D., Jordan,
J., and Seals, D. R. (2003). Barore-
flex buffering is reduced with age
in healthy men. Circulation 107,
Kajimura, N., Uchiyama,M., Takayama,
Y., Uchida, S., Uema, T., Kato, M.,
Sekimoto, M., Watanabe, T., Naka-
jima, T., Horikoshi, S., Ogawa, K.,
Nishikawa, M., Hiroki, M., Kudo, Y.,
Matsuda, H., Okawa, M., and Taka-
hashi, K. (1999). Activity of mid-
brain reticular formation and neo-
cortex during the progression of
human non-rapid eye movement
sleep. J. Neurosci. 19, 10065–10073.
Kjaer, T. W., Law, I., Wiltschiotz, G.,
Paulson, O. B., and Madsen, P. L.
(2002). Regional cerebral blood flow
during light sleep – a H(2)(15)O-
PET study. J. Sleep Res. 11, 201–207.
Krauchi, K., Cajochen, C., Danilenko,K.
V., and Wirz-Justice, A. (1997). The
hypothermic effect of late evening
melatonin does not block the phase
delay induced by concurrent bright
light in human subjects. Neurosci.
Lett. 232, 57–61.
Kumar, V. M. (2010). Sleep is neither a
passive nor an active phenomenon.
Sleep Biol. Rhythms 8, 163–169.
Lang, R., Dehof, K., Meurer, K. A., and
Kaufmann, W. (1979). Sympathetic
activity and transcendental medita-
tion. J. Neural Transm. 44, 117–135.
Lazar, S. W., Kerr, C. E., Wasserman, R.
H., Gray, J. R., Greve, D. N., Tread-
way, M. T., McGarvey, M., Quinn, B.
T.,Dusek, J. A., Benson, H., Rauch, S.
L., Moore,C. I., and Fischl, B. (2005).
Meditation experience is associated
with increased cortical thickness.
Neuroreport 16, 1893–1897.
Lou, H. C., Kjaer, T. W., Friberg, L.,
Wildschiodtz, G., Holm, S., and
Nowak, M. (1999).A 15O-H2O PET
study of meditation and the resting
state of normal consciousness. Hum.
Brain Mapp. 7, 98–105.
Lutz, A., Greischar, L. L., Rawlings,
N. B., Ricard, M., and Davidson,
R. J. (2004). Long-term meditators
self-induce high-amplitude gamma
synchrony during mental practice.
Proc. Natl. Acad. Sci. U.S.A. 101,
MacLean, C. R., Walton, K. G., Wen-
neberg, S. R., Levitsky, D. K., Man-
darino, J. P., Waziri, R., Hillis, S. L.,
and Schneider, R. H. (1997). Effects
of the transcendental meditation
program on adaptive mechanisms:
changes in hormone levels and
responses to stress after 4 months
of practice. Psychoneuroendocrinol-
ogy 22, 277–295.
Maestroni, G. J. (2001). The
immunotherapeutic potential
of melatonin. Expert Opin. Investig.
Drugs 10, 467–476.
Martinez, D., and Lenz, M. C. (2010).
Circadian rhythm sleep disorders.
Indian J. Med. Res. 131, 141–149.
Mason, L. I., Alexander, C. N., Travis,
F. T., Marsh, G., Orme-Johnson, D.
W., Gackenbach, J., Mason, D. C.,
Rainforth, M., and Walton, K. G.
(1997). Electrophysiological corre-
lates of higher states of conscious-
ness during sleep in long-term prac-
titioners of the transcendental med-
itation program. Sleep 20, 102–110.
Massion, A. O., Teas, J., Hebert, J. R.,
Wertheimer, M. D., and Kabat-Zinn,
J. (1995). Meditation,melatonin and
breast/prostate cancer: hypothesis
and preliminary data. Med. Hypothe-
ses 44, 39–46.
Mourtazaev, M. S., Kemp, B., Zwinder-
man, A. H., and Kamphuisen, H. A.
(1995). Age and gender affect differ-
ent characteristics of slow waves in
the sleep EEG. Sleep 18, 557–564.
Newberg, A. B., and Iversen, J. (2003).
The neural basis of the complex
mental task of meditation: neuro-
transmitter and neurochemical con-
siderations. Med. Hypotheses 61,
Nicolas, A., Petit, D., Rompre, S., and
Montplaisir, J. (2001). Sleep spin-
dle characteristics in healthy sub-
jects of different age groups. Clin
Neurophysiol 112, 521–527.
Ong, J. C., Shapiro, S. L., and Manber,
R. (2008). Combining mindfulness
meditation with cognitive-behavior
therapy for insomnia: a treatment-
development study. Behav. Ther. 39,
Otzenberger,H., Simon, C., Gronfier,C.,
and Brandenberger, G. (1997). Tem-
poral relationship between dynamic
heart rate variability and electroen-
cephalographic activity during sleep
in man. Neurosci. Lett. 229, 173–176.
Pagnoni, G., and Cekic, M. (2007).
Age effects on gray matter vol-
ume and attentional performance in
Zen meditation. Neurobiol.Aging 28,
Pandi-Perumal, S. R., Srinivasan, V.,
Maestroni, G. J., Cardinali, D. P.,
Poeggeler, B., and Hardeland, R.
(2006). Melatonin: nature’s most
versatile biological signal? FEBS J.
273, 2813–2838.
Pedemonte, M., Rodriguez-Alvez, A.,
and Velluti, R. A. (2005). Electroen-
cephalographic frequencies associ-
ated with heart changes in RR inter-
val variability during paradoxical
sleep. Auton. Neurosci. 123, 82–86.
Pivik, R. T.,Busby, K. A., Gill, E., Hunter,
P., and Nevins, R. (1996). Heart rate
variations during sleep in preadoles-
cents. Sleep 19, 117–135.
Ramaekers, D., Ector, H., and Aubert,
A. E. (1999). The influence of age
and gender on heart rate variabil-
ity (HRV). J. Am. Coll. Cardiol. 33,
Ravindra, P. N., Sulekha, S.,
Sathyaprabha, T. N., Pradhan,
N., Raju, T. R., and Kutty, B. M.
(2010). Practitioners of vipassana
meditation exhibit enhanced slow
wave sleep and REM sleep states
across different age groups. Sleep
Biol. Rhythms 8, 34–41.
Reiter, R. J. (1995). Oxygen radi-
cal detoxification processes during
aging: the functional importance
of melatonin. Aging (Milano) 7,
Sack, R. L., Lewy, A. J., Erb, D. L.,
Vollmer, W. M., and Singer, C. M.
(1986). Human melatonin produc-
tion decreases with age. J. Pineal Res.
3, 379–388.
Sibinga, E. M., Kerrigan, D.,Stewart, M.,
Johnson, K., Magyari, T.,and Ellen, J.
M. (2011). Mindfulness-based stress
reduction for urban youth. J. Altern.
Complement. Med. 17, 213–218.
Somers, V. K., Dyken, M. E., Mark,
A. L., and Abboud, F. M. (1993).
Sympathetic-nerve activity during
sleep in normal subjects. N. Engl. J.
Med. 328, 303–307.
Sulekha, S., Thennarasu, K.,
Vedamurthachar, A., Raju, T.
R., and Kutty, B. M. (2006). Eval-
uation of sleep architecture in
practitioners of Sudarshan Kriya
yoga and Vipassana meditation.
Sleep Biol. Rhythms 4, 207–214.
Tang, Y. Y., Ma, Y., Fan, Y., Feng, H.,
Wang, J., Feng, S., Lu, Q., Hu, B.,
Lin, Y., Li, J., Zhang, Y., Wang, Y.,
Zhou, L., and Fan, M. (2009). Cen-
tral and autonomic nervous system
interaction is altered by short-term
meditation. Proc. Natl. Acad. Sci.
U.S.A. 106, 8865–8870.
Tooley, G. A., Armstrong, S. M., Nor-
man, T. R., and Sali, A. (2000). Acute
increases in night-time plasma mela-
tonin levels following a period of
meditation. Biol. Psychol. 53, 69–78.
Travis, F., and Shear, J. (2010). Focused
attention, open monitoring and
automatic self-transcending: cat-
egories to organize meditations
from Vedic, Buddhist and Chi-
nese traditions. Conscious. Cogn. 19,
1110–1118. April 2012 | Volume 3 | Article 54 | 3
Nagendra et al. Meditation and sleep
Trinder, J., Kleiman, J., Carrington, M.,
Smith, S., Breen, S., Tan, N., and
Kim, Y. (2001). Autonomic activity
during human sleep as a function of
time and sleep stage. J. Sleep Res. 10,
von Gall, C., Stehle, J. H., and Weaver,
D. R. (2002). Mammalian melatonin
receptors: molecular biology and
signal transduction. Cell Tissue Res.
309, 151–162.
Wallace, R. K. (1970). Physiological
effects of transcendental meditation.
Rev. Bras. Med. 27, 397–401.
Wallace, R. K., Benson, H., and
Wilson, A. F. (1971). A wake-
ful hypometabolic physiologic
state. Am. J. Physiol. 221,
Werner, O. R., Wallace, R. K., Charles,
B., Janssen, G., Stryker, T., and
Chalmers, R. A. (1986). Long-
term endocrinologic changes in
subjects practicing the transcen-
dental meditation and TM-Sidhi
program. Psychosom. Med. 48,
Wu, S. D., and Lo,P. C. (2008). Inward-
attention meditation increases
parasympathetic activity: a study
based on heart rate variability.
Biomed. Res. 29, 245–250.
Young, J. D., and Taylor,E. (1998). Med-
itation as a voluntary hypometabolic
state of biological estivation. News
Physiol. Sci. 13, 149–153.
Zeidan, F., Johnson, S. K., Gordon, N.
S., and Goolkasian, P. (2010). Effects
of brief and sham mindfulness med-
itation on mood and cardiovascu-
lar variables. J. Altern. Complement.
Med. 16, 867–873.
Conflict of Interest Statement: The
authors declare that the research was
conducted in the absence of any com-
mercial or financial relationships that
could be construed as a potential
conflict of interest.
Received: 21 March 2012; paper pending
published: 26 March 2012; accepted: 27
March 2012; published online: 18 April
Citation: Nagendra RP, Maruthai N and
Kutty BM (2012) Meditation and its reg-
ulatory role on sleep. Front. Neur. 3:54.
doi: 10.3389/fneur.2012.00054
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Frontiers in Neurology | Sleep and Chronobiology April 2012 | Volume 3 | Article 54 | 4
... Sleep is one such autoregulatory mechanism of the body, essential to perform many vital physiological functions such as development, clearing of brain waste, and modulation of the body's immune responses [5], and hence deprivation of this function increases the risk of disorders like stress, anxiety, depression, obesity, hypertension, dyslipidemia, diabetes, cardiovascular diseases, cancer [6] and can potentially lead to substance abuse and even suicidal ideation. At the same time, efficacious behavioral treatments such as mind-body therapies, biofeedback, guided imagery, hypnotherapy, mind-body movement, meditation, relaxation techniques, yoga, and even spiritual practices or other contemplative techniques, that help reduce stress and improve sleep exist alongside pharmacological management of insomnia and sleep disturbances [7][8][9][10][11][12][13][14][15]. ...
... Research establishes that such practices significantly improve sleep quality, duration and other aspects of sleep, both in clinical as well as non-clinical populations: meditation in particular impacts various components of the body's sleep generating mechanisms and alters them [11]. Although there are various kinds of meditation, there are commonalities between various techniques, and all of them are beneficial to some degree or other for the reduction of stress, anxiety, depression, and improvement of pain [10-13, 15, 16]. ...
... A recent meta-analysis by Rusch et al. [17], which focused on RCTs involving populations with significant sleep disturbance, also compellingly suggests that meditation improves sleep quality even in such populations [17]. The beneficial impact of certain types of meditation on sleep has been extensively studied, particularly mindfulness meditation and mindfulness-based stress reduction (MBSR) exercises, along with Vipassana, other kinds of transcendental meditation (TM) and Sudarshan Kriya Yoga [11,[17][18][19]]. An inverse association for higher frequency of practice of Sudarshan Kriya Yoga and lower odds of poor Sleep Quality (OR = 0.52; 95% CI 0.28-0.94) ...
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Purpose Disturbed sleep and other sleep-related problems have a negative impact on the human mind and body. Meditation practices are reported to improve physiological functions and might also have a positive impact on regulating sleep. This research investigates the efficacy of an advanced mind–body medicine intervention, called Hollow and Empty Meditation (HEM), on improving sleep quality. Methods The study was a single-arm open-trial pilot study which assessed 413 adults who underwent a 4-day meditation retreat offered by the Art of Living, called the Advanced Meditation Program (AMP), and experienced a novel meditation—HEM. Results were measured using a self-report questionnaire, the Pittsburgh Sleep Quality Index (PSQI), which was administered to the participants thrice: on the first day of the program (pre-intervention), immediately after program (post-intervention/Day 4), and on Day 40 (D40) after the program. Results There was a significant difference in pre–post and pre–D40 scores in the population. Both sleep quality and sleep duration showed an improvement immediately after the AMP (post), and the residual impact was still experienced at D40, especially with the group with age > 36 years. Conclusions The use of HEM resulted in improvement in sleep quality not just immediately after the program, but had longer-term effects that extended over several weeks, helping remediate sleep problems among younger adults as well as older ones. It resulted in improvement in sleep quality as well as reduction in sleep-related daytime impairment, which have substantial constructive implications for well-being, everyday functioning and quality of life.
... These inconsistencies on the effect of meditation practices on hormones are not yet resolved though it was first reported decades back 38 , and the influence of meditation practice on sleep-associated hormonal profiles is sparingly evaluated. Our earlier studies have shown that long-term Vipassana meditation practice, by inducing neural plasticity changes and modulating cardiac autonomic activity will positively influence sleep architecture 16,39 . In the present manuscript, we have evaluated sleep-related hormones and their correlation with sleep stages among long-term practitioners of Vipassana meditation. ...
... An increase in DHEA with cortisol levels in meditators reflects the positive influence of meditation practice on the HPA axis. This humoral correlate with sleep architecture is in addition to the neural plasticity and autonomic modulatory effects of Vipassana meditation practice on sleep 11,16,39 . This study provides ample evidence to explore the mechanisms that probably could have been involved in the beneficial effect of mindfulness meditation intervention in insomnia. ...
Objectives: Meditation practices positively influence the neural, hormonal and autonomic systems. We have demonstrated that long-term practice of mindfulness meditation increases N3 and rapid eye movement (REM) sleep stages and bring efficient autonomic modulation during sleep. In the present study, the probable humoral correlation that could bring about these changes is evaluated. Material and Methods: Long-term Vipassana meditators (n=41) and controls (n=24) (males, 30-60 years of age) underwent a two-day consecutive whole night polysomnography recording. During the second day, with exposure to 100Lux brightness, blood was sampled from the antecubital vein between 8-9 PM and in subsequent early morning. Sleep stage was scored as per American Society of Sleep Medicine (ASSM) guidelines for the second-day recording. Sleep-related hormones were estimated - melatonin by radioimmunoassay; dehydroepiandrosterone (DHEA), cortisol, growth hormone (GH) and prolactin with enzyme-linked immunosorbent assay (ELISA); DHEA/cortisol ratio was calculated. Percentage of sleep stages and hormonal levels were compared between both groups using independent ‘t’ test and Pearson’s correlation was estimated between sleep stages and hormonal levels. Results: Meditators showed increased N3, REM sleep stages. Though evening cortisol was comparable between the two groups; early morning cortisol, diurnal DHEA and melatonin were significantly higher in meditators. Diurnal DHEA correlated significantly with the N3 sleep stage in meditators. Discussion: Higher diurnal DHEA despite variations in corresponding cortisol in meditators demonstrates that long-term Vipassana meditation practice modulates the hypothalamicpituitary-adrenal (HPA) axis and thereby influences sleep. Thus, the study provides evidence to explore the mechanism most likely involved with mindfulness meditation intervention in insomnia.
... Meditation practices increase melatonin by restricting its hepatic metabolism or increasing pineal gland synthesis. Considering the melatonin function in sleep management, mediation activities may improve sleep quality by increased release of melatonin [50]. ...
... Sleep has been correlated with lowered heart rate, blood pressure, breath rate and rhythm, oxygen intake, fear or excitations, and reduced basal metabolic level [50]. In cardiovascular conditions, decreased level of circulating melatonin has been observed. ...
... Meditation practices increase melatonin by restricting its hepatic metabolism or increasing pineal gland synthesis. Considering the melatonin function in sleep management, mediation activities may improve sleep quality by increased release of melatonin [50]. ...
... Sleep has been correlated with lowered heart rate, blood pressure, breath rate and rhythm, oxygen intake, fear or excitations, and reduced basal metabolic level [50]. In cardiovascular conditions, decreased level of circulating melatonin has been observed. ...
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Cardiovascular diseases are the leading cause of disease burden globally. Sleep and cardiovascular connection represent a two-way lane. Recently, many reports have suggested that meditation practices have a beneficial effect on cardiovascular diseases. But the exact mechanism was not known. Several reports suggest that meditation induces the secretion of melatonin. The rhythm of melatonin follows a sleep pattern. Thus, the present hypothesis correlates the plausible mechanisms involved in meditation with enhancing cardiac health through melatonin synthesis. An altered modern lifestyle decreases the level of melatonin which disrupts the circadian rhythm, and subsequently, there is a high incidence of cardiovascular diseases. The disrupted cardiac energy metabolism is distorted due to altered circadian rhythm with elevated ROS. The increased level of ROS activates the inflammatory mediators' cytokines and damages the DNA, resulting in altered cardiac physiology. Melatonin regulates the circadian rhythm and acts as a silent regulator for the cardiac energy balance. Melatonin is the central player of circadian rhythm, and it protects cardiomyocytes by acting as an antioxidant, anti-inflammatory mediator, and repairing DNA damage. Meditation induces melatonin and improves cardiac health through the aforementioned mechanisms.
... The techniques utilized include identifying activities that provide energy, scheduling joy activities (38), positive reflection (39), cognitive reframing (40), gratitude exercises (41), finding acceptance (42), and sleep meditations (43). These comprise a mix of positive psychology, acceptance and commitment therapy (ACT), and CBT techniques that encourage the development of therapeutic skills. ...
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The present study aims to examine whether users perceive a therapeutic alliance with an AI conversational agent (Wysa) and observe changes in the t‘herapeutic alliance over a brief time period. A sample of users who screened positively on the PHQ-4 for anxiety or depression symptoms (N = 1,205) of the digital mental health application (app) Wysa were administered the WAI-SR within 5 days of installing the app and gave a second assessment on the same measure after 3 days (N = 226). The anonymised transcripts of user's conversations with Wysa were also examined through content analysis for unprompted elements of bonding between the user and Wysa (N = 950). Within 5 days of initial app use, the mean WAI-SR score was 3.64 (SD 0.81) and the mean bond subscale score was 3.98 (SD 0.94). Three days later, the mean WAI-SR score increased to 3.75 (SD 0.80) and the mean bond subscale score increased to 4.05 (SD 0.91). There was no significant difference in the alliance scores between Assessment 1 and Assessment 2.These mean bond subscale scores were found to be comparable to the scores obtained in recent literature on traditional, outpatient-individual CBT, internet CBT and group CBT. Content analysis of the transcripts of user conversations with the CA (Wysa) also revealed elements of bonding such as gratitude, self-disclosed impact, and personification. The user's therapeutic alliance scores improved over time and were comparable to ratings from previous studies on alliance in human-delivered face-to-face psychotherapy with clinical populations. This study provides critical support for the utilization of digital mental health services, based on the evidence of the establishment of an alliance.
... Our results are congruent with those findings. The participants in the MMRS group were taught a locally developed, medium-to-low-intensity exercise, which was coupled with meditation and deep breathing to lower symptom-related stress and promoted sleep quality, through activating the parasympathetic nervous system, thus decreasing alarm reactions [29]. ...
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Sleep disturbance is considered one of the hallmarks of the common symptoms experienced by women during and after menopause. This study aimed to compare the effectiveness of two different multiple-component, sleep-promoting interventions on the sleep quality of menopausal women. A quasi-experimental study and repeated measured design, with a four-week sleep-promoting intervention, was conducted. A total of 123 eligible participants were recruited from a health center in northern Taiwan and divided into the progressive muscle relaxation plus sleep hygiene (PMRS), the meditative movement relaxation plus sleep hygiene (MMRS), or control group at a 1:1:1 ratio. The Chinese version of Pittsburgh sleep quality index and actigraphy were used to assess the sleep disturbances of menopausal women. The subjective sleep data was collected before, immediately after the intervention, 8 weeks, and 12 weeks after the intervention. The results showed that the global score of subjective sleep quality and its components were significantly improved after both interventions. Additionally, the MMRS was superior to the PMRS for subjective sleep quality. Moreover, the objective sleep indices indicated that sleep latency was reduced after both the interventions. These findings can serve as a reference for nurses when caring for menopausal women with sleep disturbance.
... There are several mind-body practices and interventions such as yoga [30,31] and cognitive behavioral therapies (CBT) [32], which improve the quality and duration of sleep. A large body of research has been devoted to investigating the effects of meditation techniques like mindfulness meditation or transcendental meditation on sleep [33][34][35]. The immediate beneficial role that SKY might have on sleep is understudied. ...
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Purpose Sudarshan Kriya Yoga (SKY) is an advanced yogic breathing technique with a demonstrated impact on human physical and mental health. Even so, very few studies have observed its effect on sleep. This is the first study evaluating the impact of SKY as an intervention on sleep quality among Indian population. This study assessed both the immediate and prolonged effect of SKY on sleep quality. The secondary objective of the study was to evaluate the association between frequency of SKY practice and sleep quality. Methods This was a single arm open-trial study, which included 473 participants. All participants underwent a 3-day SKY workshop offered by the Art of Living, and were assessed for sleep quality using the Pittsburgh Sleep Quality Index (PSQI) questionnaire, administered to the participants before the program (pre-intervention), immediately after the program (post-intervention), and at Day 40 (D40) after the program. Responses were grouped according to age, gender, and frequency of practice. The impact of the frequency of SKY practice on sleep quality was also investigated. Results The quality of sleep improved with SKY practice across the study population. Women recorded inferior quality of sleep at the beginning of the study, but experienced a greater improvement in sleep quality after the SKY practice, as compared to men. The younger population seemed to benefit over the long-term, while the older population had an immediate improvement in sleep quality, however, they were not able to sustain it. The effect size varied with the frequency of practice. Sleep quality improved markedly among those who practiced SKY daily, indicating an association between the frequency of SKY practice and its efficiency in improving sleep quality. Conclusion The results demonstrate the efficacy of SKY in improving sleep quality across populations, irrespective of gender or age. This is indicative of the beneficial role of SKY in treating psychological disorders such as insomnia. The effect varies with the frequency of practice, with more frequent practice yielding better quality of sleep.
... Medication practice helps in maintaining homeostasis in the body via producing Global changes in the brain including sleep and its regulation. [45] The practice of Yoga improves sleep architecture and mental well-being in young and middle-aged adults. Sudershan Kriya and Vipassana practice prevented the decline in NREM and Vipassana increased REM sleep in healthy adults 31-55 years. ...
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Stress is one of the major problems globally, associated with poor sleep quality and cognitive dysfunction. Modern society is plagued by sleep disturbances, either due to professional demands or lifestyle or both the aspects, often leading to reduced alertness and compromised mental function, besides the well documented ill effects of disturbed sleep on physiological functions. This pertinent issue needs to be addressed. Yoga is an ancient Indian science, philosophy and way of life. Recently, yoga practice has become increasingly popular worldwide. Yoga practice is an adjunct effective for stress, sleep and associated disorders. There are limited well controlled published studies conducted in this area. We reviewed the available literature including the effect of modern lifestyle in children, adolescents, adults and geriatric population. The role of yoga and meditation in optimizing sleep architecture and cognitive functions leading to optimal brain functioning in normal and diseased state is discussed. We included articles published in English with no fixed time duration for literature search. Literature was searched mainly by using PubMed and Science Direct search engines and critically examined. Studies have revealed positive effects of yoga on sleep and cognitive skills among healthy adults as well as patients of some neurological diseases. Further, on evaluating the published studies, it is concluded that sleep and cognitive functions are optimized by yoga practice, which brings about changes in autonomic function, structural changes, changes in metabolism, neurochemistry and improved functional brain network connectivity in key regions of the brain.
Socially disadvantaged groups with restricted self-determination or autonomy are disproportionately burdened by poor sleep health, which likely contributes to disparities in the wide array of commonly observed, recalcitrant poor health outcomes. The aim of this chapter is to identify and summarize the thrust of the evidence regarding sleep health disparities among mainly racial/ethnic minorities as well as summarize both determinants that are largely modifiable and health consequences of sleep health disparities using selective studies as key examples. To better conceptualize how societal ills can produce observable biological differences across socially constructed groups, I use the socioecological framework with a life-course perspective as a conceptual model to frame the biological embodiment of social disadvantage in ways that can lead to sleep disparities and its health sequelae. Directions for future research will center around a range of potentially effective interventions and research approaches to address sleep health disparities in order to achieve sleep equity.
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Stress has been implicated in both somatic and mental disorders. The mechanisms by which stress leads to poor health are largely unknown. However, studies in animals suggest that chronic stress causes high basal cortisol and low cortisol response to acute stressors and that such changes may contribute to disease. Previous studies of the Transcendental Mediation® (TM) technique as a possible means of countering effects of stress have reported altered levels of several hormones both during the practice and longitudinally after regular practice of this technique. In this prospective, random assignment study, changes in baseline levels and acute responses to laboratory stressors were examined for four hormones—cortisol, growth hormone, thyroid-stimulating hormone and testosterone—before and after 4 months of either the TM technique or a stress education control condition. At pre- and post-test, blood was withdrawn continuously through an indwelling catheter, and plasma or serum samples were frozen for later analysis by radioimmunoassay. The results showed significantly different changes for the two groups, or trends toward significance, for each hormone over the 4 months. In the TM group, but not in the controls, basal cortisol level and average cortisol across the stress session decreased from pre- to post-test. Cortisol responsiveness to stressors, however, increased in the TM group compared to controls. The baselines and/or stress responsiveness for TSH and GH changed in opposite directions for the groups, as did the testosterone baseline. Overall, the cortisol and testosterone results appear to support previous data suggesting that repeated practice of the TM technique reverses effects of chronic stress significant for health. The observed group difference in the change of GH regulation may derive from the cortisol differences, while the TSH results are not related easily to earlier findings on the effects of chronic stress.
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The objectives of this study were to assess the general acceptability and to assess domains of potential effect of a mindfulness-based stress reduction (MBSR) program for human immunodeficiency virus (HIV)-infected and at-risk urban youth. Thirteen-to twenty-one-year-old youth were recruited from the pediatric primary care clinic of an urban tertiary care hospital to participate in 4 MBSR groups. Each MBSR group consisted of nine weekly sessions of MBSR instruction. This mixed-methods evaluation consisted of quantitative data--attendance, psychologic symptoms (Symptom Checklist 90-Revised), and quality of life (Child Health and Illness Profile-Adolescent Edition)--and qualitative data--in-depth individual interviews conducted in a convenience sample of participants until interview themes were saturated. Analysis involved comparison of pre- and postintervention surveys and content analysis of interviews. Thirty-three (33) youth attended at least one MBSR session. Of the 33 who attended any sessions, 26 youth (79%) attended the majority of the MBSR sessions and were considered "program completers." Among program completers, 11 were HIV-infected, 77% were female, all were African American, and the average age was 16.8 years. Quantitative data show that following the MBSR program, participants had a significant reduction in hostility (p = 0.02), general discomfort (p = 0.01), and emotional discomfort (p = 0.02). Qualitative data (n = 10) show perceived improvements in interpersonal relationships (including less conflict), school achievement, physical health, and reduced stress. The data suggest that MBSR instruction for urban youth may have a positive effect in domains related to hostility, interpersonal relationships, school achievement, and physical health. However, because of the small sample size and lack of control group, it cannot be distinguished whether the changes observed are due to MBSR or to nonspecific group effects. Further controlled trials should include assessment of the MBSR program's efficacy in these domains.
According to traditional belief, prolonged wakefulness during the day is followed by brain rest at night in the form of sleep. This passive theory of sleep was replaced by the active sleep genesis concept, mainly after the realization that brain activity is only slightly reduced during sleep. There is now growing evidence to suggest that sleep is auto-regulatory and that it is not necessary to attribute sleep genesis to either an active or a passive mechanism. © 2010 The Author. Journal compilation
The aim of the present study was to examine whether the neural structures subserving meditation can be reproducibly measured, and, if so, whether they are different from those supporting the resting state of normal consciousness. Cerebral blood flow distribution was investigated with the 15O-H2O PET technique in nine young adults, who were highly experienced yoga teachers, during the relaxation meditation (Yoga Nidra), and during the resting state of normal consciousness. In addition, global CBF was measured in two of the subjects. Spectral EEG analysis was performed throughout the investigations. In meditation, differential activity was seen, with the noticeable exception of V1, in the posterior sensory and associative cortices known to participate in imagery tasks. In the resting state of normal consciousness (compared with meditation as a baseline), differential activity was found in dorso-lateral and orbital frontal cortex, anterior cingulate gyri, left temporal gyri, left inferior parietal lobule, striatal and thalamic regions, pons and cerebellar vermis and hemispheres, structures thought to support an executive attentional network. The mean global flow remained unchanged for both subjects throughout the investigation (39 ± 5 and 38 ± 4 ml/100 g/min, uncorrected for partial volume effects). It is concluded that the H215O PET method may measure CBF distribution in the meditative state as well as during the resting state of normal consciousness, and that characteristic patterns of neural activity support each state. These findings enhance our understanding of the neural basis of different aspects of consciousness. Hum. Brain Mapping 7:98–105, 1999. © 1999 Wiley-Liss, Inc.
Intense meditation practices influence brain functions in different ways and at different levels. Earlier studies have shown that meditation practices help to organize sleep–wake behavior. In the present study, we evaluated the sleep architecture of vipassana meditators across different age groups. Whole-night polysomnography was carried out in healthy male subjects between 30 and 60 years of age from control (n= 46) and meditation (n= 45) groups. They were further divided into younger- (30–39 years), middle- (40–49 years), and older-aged (50–60 years) groups. Sleep variables were evaluated from subjects who had a sleep efficiency index more than 85%. The sleep architecture of vipassana meditators was different from that of control groups. Vipassana meditators showed enhanced slow wave sleep and rapid eye movement sleep states with an enhanced number of sleep cycles across all age groups. When compared to meditators, the control groups exhibited pronounced age-associated decrease in slow wave sleep states. Our study suggests that vipassana meditation helps to establish a proper sleep structure in old age, probably through its capacity to induce neuronal plasticity events leading to stronger network synchronization and cortical synaptic strengthening.
The purpose of this study was to investigate the effects of time of year and demographic variables on the amplitude of melatonin production in normal human subjects. Melatonin production was estimated by measuring the overnight excretion of its major urinary metabolite, 6-hydroxymelatonin. Urine was collected on three consecutive nights in the summer from a sample of 60 normal subjects balanced for sex and age. The collections were repeated in a subgroup during the winter. Melatonin production clearly declined with age but was not influenced by other demographic variables or by season of the year.
Yoga is an ancient Indian science and way of life that has been described in the traditional texts as a systematic method of achieving the highest possible functional harmony between body and mind. Yogic practices are claimed to enhance the quality of sleep. Electrophysiological correlates associated with the higher states of consciousness have been reported in long-term practitioners of transcendental meditation during deep sleep states. The present study was carried out to assess sleep architecture in Sudarshan Kriya Yoga (SKY) and Vipassana meditators. This was to ascertain the differences, if any, in sleep architecture following yogic practices. Whole night polysomnographic recordings were carried out in 78 healthy male subjects belonging to control and yoga groups. The groups studied were aged between 20 and 30-years-old (younger) and 31 to 55-years-old (middle-aged). The sleep architecture was comparable among the younger control and yoga groups. While slow wave sleep (non-REM (rapid eye movement) S3 and S4) had reduced to 3.7 percent in the middle-aged control group, participants of the middle-aged yoga groups (both SKY and Vipassana) showed no such decline in slow wave sleep states, which was experienced by 11.76 and 12.76 percent, respectively, of the SKY and Vipassana groups. However, Vipassana practitioners showed a significant enhancement (P < 0.001) in their REM sleep state from that of the age-matched control subjects and also from their SKY counterparts. Yoga practices help to retain slow wave sleep and enhance the REM sleep state in the middle age; they appear to retain a younger biological age as far as sleep is concerned. Overall, the study demonstrates the possible beneficial role of yoga in sleep–wakefulness behavior.
This is the first report on the distribution of regional cerebral blood flow (rCBF) changes during stage-1 sleep or somnolence. Two hypotheses were tested: (A) that rCBF differed between the awake relaxed state and stage-1 sleep, (B) that hypnagogic hallucinations frequently experienced at sleep onset would be accompanied by measurable changes in rCBF using positron emission tomography (PET). Eight subjects were PET-scanned with 15O-labeled water injection in three conditions: awake, stage-1 sleep with reportable experiences and stage-1 sleep without reportable experiences. Electroencephalography (EEG) was performed continuously during the experiment. Sleep interviews were performed after each scan. The EEG was scored blindly to determine sleep stage. The sleep interviews revealed a substantial increase in how unrealistic and how leaping the thoughts were during stage-1 sleep. During sleep there was a relative flow increase in the occipital lobes and a relative flow decrease in the bilateral cerebellum, the bilateral posterior parietal cortex, the right premotor cortex and the left thalamus. Hypnagogic experiences seemed not to be associated with any relative flow changes. The topography of the occipital activation during stage-1 sleep supports a hypothesis of this state being a state of imagery. The rCBF decreases in premotor cortex, thalamus and cerebellum could be indicative of a general decline in preparedness for goal directed action during stage-1 sleep. Stage-1 sleep seems more similar to other forms of altered awareness, for example, relaxation meditation than to deeper sleep stages. We are of the opinion that stage-1 sleep represents the dreaming state of wakefulness, while rapid eye movement (REM) sleep reflects the dreaming state of the unaware, sleeping brain.
To determine whether a period of meditation could influence melatonin levels, two groups of meditators were tested in a repeated measures design for changes in plasma melatonin levels at midnight. Experienced meditators practising either TM-Sidhi or another internationally well known form of yoga showed significantly higher plasma melatonin levels in the period immediately following meditation compared with the same period at the same time on a control night. It is concluded that meditation, at least in the two forms studied here, can affect plasma melatonin levels. It remains to be determined whether this is achieved through decreased hepatic metabolism of the hormone or via a direct effect on pineal physiology. Either way, facilitation of higher physiological melatonin levels at appropriate times of day might be one avenue through which the claimed health promoting effects of meditation occur.
This constant routine study (n=9 men) compared the phase delay of the circadian system induced by a single pulse of evening light (5000 lx at 2100–2400 h) in the presence or absence of exogenous melatonin (5 mg p.o. at 2040 h). On the treatment day, light and melatonin protracted and accelerated, respectively, the evening decline in core body temperature (CBT). Subjective sleepiness ratings showed parallel shifts, the earlier the decline in CBT, the sleepier. On the post-treatment day, light induced a phase delay in the mid-range crossing time of CBT decline independent of whether melatonin was co-administered or not. Subjective sleepiness was delayed in parallel. The phase delay of the circadian system by evening light appears to be independent of an immediate hyperthermic effect and is not mediated by melatonin.