title: Time estimation during nocturnal sleep in human subjects.
abstract: It has been postulated that time estimation during nocturnal sleep in humans can be explained by an interval timing clock inside the brain. However, no systematic investigations have been carried out with respect to how the human brain perceives the passage of time during sleep. The brain mechanisms of over- or underestimation of time spent in sleep have not yet been clarified. Here, we carried out an experimental study in which 11 healthy volunteers participated in time estimation trials scheduled six times during 9 h nocturnal sleep periods, under carefully controlled conditions. The time estimation ratio (TER: a ratio of subjective passage of time to actual time interval) decreased significantly from the first to the sixth trial. Individual TER was positively correlated with slow wave sleep prior to the trial, while it was negatively correlated with REM sleep. Our results indicate that the human brain has an ability to estimate the passage of time during nocturnal sleep without referring to time cues, and that the accuracy of this function fluctuates from overestimation in the early hours of sleep to underestimation in the last hours of sleep.
authors.affiliation: Department of Life Sciences and Bio-informatics, Graduate School of Allied Health Sciences, Tokyo Medical and Dental University, Yushima, Bunkyo, Tokyo 113-0034, Japan.
authors.forename: Sayaka
authors.initials: S
authors.lastname: Aritake
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Hirokuni
authors.initials: H
authors.lastname: Tagaya
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kuriyama
authors.forename: Akiko
authors.initials: A
authors.lastname: Ozaki
authors.forename: Xin
authors.initials: X
authors.lastname: Tan
authors.forename: Kayo
authors.initials: K
authors.lastname: Shibui
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Kamei
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Okubo
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Takahashi
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001921:Brain / Q000502:physiology*; D002940:Circadian Rhythm / Q000502:physiology; D004569:Electroencephalography / Q000379:methods; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000379:methods; D012890:Sleep / Q000502:physiology*; D013998:Time Perception / Q000502:physiology*; D014851:Wakefulness / Q000502:physiology