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Meditation and Its Regulatory Role on Sleep

Frontiers in Neurology

April 2012
3:54

DOI:10.3389/fneur.2012.00054

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Authors:

Ravindra Nagendra

National Institute of Mental Health and Neuro Sciences

Dr Nirmala Maruthai

National Institute of Mental Health and Neuro Sciences

Bindu Kutty

National Institute of Mental Health and Neuro Sciences

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.

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MINI REVIEW ARTICLE

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,

Japan

V. Mohan Kumar, Sree ChitraTirunal

Institute for Medical Sciences and

Technology, India

*Correspondence:

Bindu M. Kutty, Department of

Neurophysiology, National Institute of

Mental Health and Neurosciences,

Bangalore 560029, India.

e-mail: bindu.nimhans@gmail.com

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

INTRODUCTION

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).

MEDITATION, BRAIN FUNCTIONS, AND SLEEP

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.

MEDITATION, AUTONOMIC ACTIVITY, AND SLEEP

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

www.frontiersin.org 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, MELATONIN, AND SLEEP

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.,

2000).

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 AS AN AUTOREGULATORY, GLOBAL PHENOMENON

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.

CONCLUSION

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

REFERENCES

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,

107–144.

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,

327–341.

Guerrero, J. M., and Reiter, R. J. (2002).

Melatonin-immune system relation-

ships. Curr. Top. Med. Chem. 2,

167–179.

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,

141–146.

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,

1770–1774.

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,

16369–16373.

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,

282–291.

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,

171–182.

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,

1623–1627.

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,

900–902.

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,

340–351.

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.

www.frontiersin.org 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,

253–264.

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,

795–799.

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,

59–66.

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

2012.

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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Exploring the Transformative Benefits of Raja Yoga Meditation: A Five-Month Journey into Mental, Emotional, and Spiritual Wellness

Article

Jan 2025

Millions of people struggle to find true happiness, which cannot be attained through wealth, material possessions, or even human relationships. True and lasting happiness arises from a deep spiritual connection with God. Raja Yoga meditation, practiced under the guidance of the Brahma Kumaris, emphasizes self-realization and a connection with the Supreme Soul. This study examines the effects of Raja Yoga meditation on beginners over a short duration of five months, focusing on its impact on mental well-being, emotional balance, and spiritual growth. The findings highlight the transformative potential of this practice in fostering inner peace and true happiness. "Individuals suffering from neurotic disorders often experience symptoms such as sadness, depression, loss of appetite, anger, anxiety, and even conditions like schizophrenia. These challenges can be alleviated by incorporating regular meditation into daily life, which promotes mental stability, emotional balance, and inner peace." Meditation activates an individual’s inner awareness, empowering them to stay centered and maintain a positive mindset regardless of the ever-changing external circumstances. This practice cultivates resilience, clarity, and a profound sense of happiness

The effects of pilates exercise on depression and sleep quality in adults: A systematic review and meta-analysis of randomized controlled trials

Article

Full-text available

Dec 2024

Background: In recent years, Pilates has become widely popular due to its distinctive training methods, drawing substantial public interest. Studies have shown that Pilates positively influences the alleviation of depressive symptoms and the enhancement of sleep quality among adults. Yet, there has been no systematic review of these findings. Thus, this research aims to assess the effects of Pilates on adult depression and sleep quality through a comprehensive review and meta-analysis, aiming to underpin exercise prescription with solid evidence. Methods: We conducted a thorough search across five databases (PubMed, Web of Science, Scopus, Embase, and Cochrane Library) for randomized controlled trials (RCTs) that examine the impacts of Pilates on adult depression and sleep quality, including studies up to September 2024. The primary endpoints were changes in depression symptoms and sleep quality. We used Review Manager 5.4 and Stata 18 for statistical analysis, calculating effect sizes with standardized mean differences (SMD) and standard deviations (SD), with confidence intervals set at 95%. The quality of included studies was assessed using the Cochrane risk assessment tool. Results: This review included 19 studies with a total of 876 participants. All studies were deemed low risk. The meta-analysis demonstrated that Pilates training significantly reduces depression symptoms (SMD = -0.77; 95% CI: [-1.00, -0.53]; P<0.01) and improves sleep quality (SMD = -0.46; 95% CI: [-0.78, -0.14]; P<0.01).

Restless sleep is associated with increased anxiety in physical therapy students: a cross sectional survey study

Article

Full-text available

Oct 2024
BMC Med Educ

Background Sleep and mental health are intimately related and shown to impact graduate students enrolled in health sciences programs, including physical therapy education. Doctorate of Physical Therapy (DPT) students’ attitudes and behaviors surrounding sleep and whether these factors are associated with mental health are unknown. This study aimed to describe sleep behaviors and attitudes of entry-level DPT students and to explore the relationship between subjectively reported sleep quality and self-reported symptoms of anxiety in these students. Methods A cross-sectional online survey consisting of the Sleep Practices and Attitudes Questionnaire (SPAQ), the Generalized Anxiety Disorder-7 (GAD-7) questionnaire, and demographic questions were used. Analyses investigated sleep behaviors and attitudes, along with the relationship (unadjusted odds ratio) between restless sleep and anxiety in DPT students in hybrid and traditional DPT programs across the United States (US). Results A total of 271 DPT students completed the survey. A majority of students reported feeling tired during most days (80.8%, n = 219), a quarter of participants (24.7%) reported having a history of trouble sleeping and four (1.5%) reported being diagnosed with a sleep disorder. Of those who reported their sleep duration, participants slept an average of 6.86 h. The mean GAD-7 score was 7.68 (SD = 4.90), suggestive of mild anxiety. Sixty-seven (24.7%) reported having a diagnosed anxiety disorder, with generalized anxiety being the most common diagnosis. Those who reported having restless sleep were 4.09 times more likely to have moderate to severe anxiety [unadjusted odds ratio = 4.09 (95% CI 2.27,7.35; p < 0.001)] compared to those who reported restful sleep. Conclusions DPT students who rated sleep as restless exhibit signs of poor subjective sleep quality associated with an increased risk of experiencing moderate to severe anxiety compared to students who had restful sleep. Students reported behaviors surrounding sleep that may contribute to anxiety. These findings have implications for including sleep and mental health education and practices within DPT programs.

Effects of a tailor-made yoga program on upper limb function and sleep quality in women with breast cancer: A pilot randomized controlled trial

Article

Full-text available

Aug 2024

Purpose Upper limb dysfunction and sleep disturbance are common and serious health problems in women with breast cancer. Yoga is a mind-body intervention which is shown to improve physical and psychological health. The aim of this study is to evaluate the effectiveness of a tailor-made yoga program on upper limb function and sleep quality in women with breast cancer. Methods A pilot randomized controlled trial (RCT) study design was used. Participants were randomly allocated to either the yoga intervention group (YG; eight weekly 60-min group-based yoga sessions) or the wait-list control group (CG). The primary outcome measures were upper limb function and sleep quality, which were assessed by the self-reported questionnaires – the shortened version of the Disabilities of the Arm, Shoulder and Hand (QuickDASH) and the Pittsburgh Sleep Quality Index (PSQI), respectively. The secondary outcome measures were upper limb muscle strength and mobility, heart rate variability (HRV), anxiety and depression, fatigue, and health-related quality of life. All participants underwent assessment at four time-points (baseline, mid-intervention, post-intervention, and 1-month follow-up). The effectiveness of the intervention was tested by two-way mixed-design repeated-measures analysis of covariance. Results For the primary outcomes, there was no significant between-group difference in the upper limb function. The YG demonstrated significantly shorter sleep latency and higher HRV, and less sleep disturbance than the CG at post-intervention, and 1-month follow-up, respectively. For the secondary outcomes, the YG demonstrated significantly improved shoulder muscle strength and arm symptoms compared to the CG from mid-intervention until the 1-month follow-up. Conclusion This pilot trial revealed that the yoga program was feasible to be implemented for women with primary stage breast cancer. Although yoga was not found to be effective in improving the upper limb function, it improved sleep latency, HRV, shoulder muscle strength and arm symptoms of women with breast cancer.

Buddhist Ethics for Improving Health and Well-Being during Pandemics Like COVID-19 with Special References to Modern Scientific Experiments

Article

Full-text available

Apr 2024

Pathompong Bodhiprasiddhinand

The purpose of this research is to examine whether Buddhist ethics can improve the health and well-being of Buddhist practitioners during pandemics like COVID-19. It is hypothesized that diseases are part of suffering, and Buddhist teachings aim to eliminate the suffering of all beings. Buddhism also offers ethical codes of conduct for its practitioners to improve their health and well-being. So, the Buddha’s teaching or Buddhist ethics, when practiced seriously, should be able to improve one’s health, physically and mentally, enhancing the well-being of all Buddhist practitioners during the spread of all pandemics including COVID-19. The present study found that Buddhist ethical practices like the chanting of Buddhist suttas and the development of mindfulness, concentration/meditation, and insight (vipassanā) can improve both physical and mental health, which are important for dealing with any pandemic, tremendously. If the cores of Buddhist ethics (morality, meditation, and wisdom) are perfectly practiced, not only will one live with good physical and mental health but one also will be able to eliminate all the mental defilements that are the root causes of all illnesses and thus enter nibbāna, the state of mind that is beyond all sources of suffering including pandemics/epidemics. More specifically, this paper highlights a set of Buddhist practices, called four bhāvanās (types of development), that can be used to improve health and well-being during any pandemic.

Changes in high-order interaction measures of synergy and redundancy during non-ordinary states of consciousness induced by meditation, hypnosis, and auto-induced cognitive trance

Article

Full-text available

Jun 2024
NEUROIMAGE

High-order interactions are required across brain regions to accomplish specific cognitive functions. These functional interdependencies are reflected by synergistic information that can be obtained by combining the information from all the sources considered and redundant information (i.e., common information provided by all the sources). However, electroencephalogram (EEG) functional connectivity is limited to pairwise interactions thereby precluding the estimation of high-order interactions. In this multicentric study, we used measures of synergistic and redundant information to study in parallel the high-order interactions between five EEG electrodes during three non-ordinary states of consciousness (NSCs): Rajyoga meditation (RM), hypnosis, and auto-induced cognitive trance (AICT). We analyzed EEG data from 22 long-term Rajyoga meditators, nine volunteers undergoing hypnosis, and 21 practitioners of AICT. We here report the within-group changes in synergy and redundancy for each NSC in comparison with the respective baseline. Since RM was practiced with open eyes, the baseline was also recorded with eyes open. During RM, synergy increased at the whole brain level in the delta and theta bands. Redundancy decreased in frontal, right central, and posterior electrodes in delta, and frontal, central, and posterior electrodes in beta1 and beta2 bands. Since the subjects kept their eyes closed during hypnosis and AICT, their baselines were also recorded with closed eyes. During hypnosis, synergy decreased in mid-frontal, temporal, and mid-centro-parietal electrodes in the delta band. The decrease was also observed in the beta2 band in the left frontal and right parietal electrodes. During AICT, synergy decreased in delta and theta bands in left-frontal, right-frontocentral, and posterior electrodes. The decrease was also observed at the whole brain level in the alpha band. However, redundancy changes during hypnosis and AICT were not significant. The subjective reports of absorption and dissociation during hypnosis and AICT, as well as the mystical experience questionnaires during AICT, showed no correlation with the estimated high-order measures. The proposed study is the first exploratory attempt to utilize the concepts of synergy and redundancy in NSCs. The differences in synergy and redundancy during different NSCs warrant further studies to relate the extracted measures with the phenomenology of the NSCs.

The use of Focused-Attention Meditation Combined with Muscle Relaxation (MR Therapy) in the treatment of Recurrent Isolated Sleep Paralysis (RISP)- two case reports

Article

Full-text available

Nov 2024

Recurrent isolated sleep paralysis (RISP) belongs to the parasomnias of the REM sleep. Currently, there are few treatment options for this disorder. Pharmacotherapy is reserved only for the most severe cases of RISP. The first-line treatment is cognitive-behavioural therapy, the availability of which is limited. A new treatment option is meditation-relaxation therapy (MR therapy), the effectiveness of which is supported by preliminary studies. Method: This article describes two case reports of the use of a new treatment technique for RISP, MR therapy, over an 8-week period. Results: In patient 1, there was a significant improvement in the form of a reduction in the number and severity of episodes of sleep paralysis, as well as worry and stress related to RISP. In patient 2, who was simultaneously diagnosed with an emotionally unstable personality and an eating disorder, there was no improvement in RISP, though a significant decrease in the severity of depressive symptoms, post-traumatic stress disorder, and normalisation of cortisol levels were observed. Conclusions: MR therapy appears to be a promising form of treatment. Both patients benefited from its use, although the effect may be limited if other psychiatric disorders coexist.

Can Sleep Tell Us How Mindful We Are?

Article

May 2024
SLEEP

Sleep effects of psychological therapies for menopausal symptoms in women with hot flashes and night sweats: A systematic review

Article

May 2024

Sleep disturbance is frequently reported by women during the menopausal transition due to various physiological changes and environmental factors. Insomnia is a critical treatment target for its deleterious effects on daytime functioning and quality of life and increased risk of developing a depressive disorder. Due to medication side effects and patient preferences, there is increased interest in the use of psychological treatments that address the myriad of menopausal symptoms, including cognitive-behavioural therapy, clinical hypnosis and mindfulness-based therapies. The objective of this article is to review the effects of psychological treatments for menopausal symptoms on sleep disturbance in peri-/postmenopausal women. We conducted a systematic review of the literature using PubMed and reference lists from inception until May 2023, including 12 studies that evaluated sleep as a secondary outcome. Most studies found that group and self-help (guided and unguided) cognitive-behavioural therapies and clinical hypnosis for menopausal symptoms have positive effects on sleep among women with significant vasomotor symptoms. There was preliminary support for mindfulness-based stress reduction. Future research including more diverse samples and women with sleep disorders is needed. Evaluating the implementation of psychological therapies in clinics where menopausal women seek care is an important next step.

The optimal exercise intervention for sleep quality in adults: A systematic review and network meta-analysis

Article

Apr 2024
PREV MED

Effects of the Transcendental Meditation program on adaptive mechanisms: changes in hormone levels and responses to stress after 4 months of practice

Article

Full-text available

Jun 1997
PSYCHONEUROENDOCRINO

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.

Mindfulness-Based Stress Reduction for Urban Youth

Article

Full-text available

Feb 2011
J ALTERN COMPLEM MED

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.

Sleep is neither a passive nor an active phenomenon

Article

Jul 2010
SLEEP BIOL RHYTHMS

Velayudhan Mohan Kumar

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

A 15O-H2O PET Study of Meditation and the Resting State of Normal Consciousness

Article

Jan 1999
HUM BRAIN MAPP

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.

Practitioners of vipassana meditation exhibit enhanced slow wave sleep and REM sleep states across different age groups

Article

Jan 2010
SLEEP BIOL RHYTHMS

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.

Human Melatonin Production Decreases With Age

Article

Oct 1986
J PINEAL RES

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.

Evaluation of Sleep architecture in practitioners of Vipassana and Sudarshana Kriya Yoga

Article

Sep 2006
SLEEP BIOL RHYTHMS

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.

Regional cerebral blood flow during light sleep - A H215O-PET study

Article

Sep 2002
J SLEEP RES

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.

Acute Increases in Nighttime Plasma Melatonin Levels Following a Period of Meditation

Article

Jun 2000
BIOL PSYCHOL

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.

The hypothermic effect of late evening melatonin does not block the phase delay induced by concurrent light in human subjects

Article

Sep 1997
NEUROSCI LETT

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.