Circadian pacemaker interferes with sleep onset at specific times each day: role in insomnia.

The human circadian pacemaker modulates our desire and ability to fall asleep at different times of day. To study this circadian component of sleep tendency, we have analyzed the sleep-wake patterns recorded from 15 free-running subjects in whom the sleep-wake cycle spontaneously desynchronized from the circadian rhythm of body temperature. The analysis indicates that the distribution of sleep onsets during free run is bimodal, with one peak at the temperature trough and, contrary to previous reports, a second peak 9-10 h later. Furthermore, there are two consistent zones in the circadian temperature cycle during which normal subjects rarely fall asleep. We hypothesize that this bimodal rhythm of sleep tendency, revealed under free-running conditions, maintains the same fixed phase relation to the circadian temperature cycle during 24-h entrainment. This would imply that normally entrained individuals should experience a peak of sleep tendency in the midafternoon and a zone of minimal sleep tendency approximately 1-3 h before habitual bedtime. Our temporal isolation data thereby account quantitatively for the timing of the afternoon siesta and suggest that malfunctions of the phasing of the circadian pacemaker may underlie the insomnia associated with sleep-scheduling disorders.

[1]  M. Siffre.  Six months alone in a cave , 1975 .

[2]  Jürgen Zulley,et al.  Interaction Between the Sleep-Wake Cycle and the Rhythm of Rectal Temperature , 1982 .

[3]  C A Czeisler,et al.  Human sleep: its duration and organization depend on its circadian phase. , 1980, Science.

[4]  G. Dörrscheidt,et al.  Advanced methods for evaluating characteristic parameters (τ, α, ϱ) of circadian rhythms , 1975 .

[5]  W. B. Webb,et al.  Sleep and waking in a time-free environment , 1974 .

[6]  Jackson Fr.  The Isolation of Biological Rhythm Mutations on the Autosomes of Drosophila melanogaster , 1983 .

[7]  J ASCHOFF.  CIRCADIAN RHYTHMS IN MAN. , 1965, Science.

[8]  M. Carskadon,et al.  Circadian variation of sleep tendency in elderly and young adult subjects. , 1982, Sleep.

[9]  R. Broughton.  Biorhythmic variations in consciousness and psychological functions. , 1975 .

[10]  S. Campbell,et al.  Napping behavior during "spontaneous internal desynchronization": sleep remains in synchrony with body temperature. , 1985, Human neurobiology.

[11]  J. Sassin,et al.  Effects of a prolonged 3-hour sleep-wake cycle on sleep stages, plasma cortisol, growth hormone and body temperature in man. , 1974, The Journal of clinical endocrinology and metabolism.

[12]  P. Lavie,et al.  Ultrashort sleep-waking schedule. III. 'Gates' and 'forbidden zones' for sleep. , 1986, Electroencephalography and clinical neurophysiology.

[13]  S H Strogatz,et al.  The mathematical structure of the human sleep-wake cycle , 1986 .

[14]  H. Agnew,et al.  Sleep efficiency for sleep-wake cycles of varied length. , 1975, Psychophysiology.

[15]  I. Zucker,et al.  Circadian rhythms in drinking behavior and locomotor activity of rats are eliminated by hypothalamic lesions. , 1972, Proceedings of the National Academy of Sciences of the United States of America.

[16]  W C Dement,et al.  Distribution of REM sleep on a 90 minute sleep-wake schedule. , 1980, Sleep.

[17]  J. Aschoff.  Desynchronization and resynchronization of human circadian rhythms. , 1969, Aerospace medicine.

[18]  R. Moore,et al.  Loss of a circadian adrenal corticosterone rhythm following suprachiasmatic lesions in the rat. , 1972, Brain research.

[19]  S. Strogatz,et al.  Bright light resets the human circadian pacemaker independent of the timing of the sleep-wake cycle. , 1986, Science.

[20]  Jürgen Aschoff,et al.  The Circadian System of Man , 1979 .

[21]  J. Waterhouse,et al.  The circadian rhythms of human subjects without timepieces or indication of the alternation of day and night , 1974, The Journal of physiology.

[22]  R. Wever.  The Circadian System of Man , 1979, Topics in Environmental Physiology and Medicine.

[23]  S. Strogatz,et al.  Circadian regulation dominates homeostatic control of sleep length and prior wake length in humans. , 1986, Sleep.

[24]  G. Chouvet,et al.  Periodicite bicircadienne du cycle veille-sommeil dans des conditions hors du temps. etude polygraphique , 1974 .

[25]  C A Czeisler,et al.  Chronotherapy: resetting the circadian clocks of patients with delayed sleep phase insomnia. , 1981, Sleep.

[26]  F. J. Evans,et al.  Appetitive and replacement naps: EEG and behavior. , 1977, Science.

[27]  J. Aschoff,et al.  Desynchronization of human circadian rhythms. , 1967, The Japanese journal of physiology.