title: Time estimation during sleep relates to the amount of slow wave sleep in humans.
abstract: Humans have the ability to estimate the amount of time that has elapsed during sleep (time estimation ability; TEA) that enables a subset of individuals to wake up at a predetermined time without referring to a watch or alarm clock. Although previous studies have indicated sleep structure as a key factor that might influence TEA during sleep, which sleep parameters could affect the TEA has not been clarified. We carried out an experimental study in which 20 healthy volunteers participated in six time estimation trials during the 9-h nighttime sleep (NS) experiment or daytime sleep (DS) experiment. The time estimation ratio (TER, ratio of the subjective estimated time interval to actual time interval) decreased significantly from the first to the sixth trial in both the NS and DS experiments. TER correlated positively with slow wave sleep (SWS) in both experiments, suggesting that SWS was a determining factor in accurate time estimation, irrespective of circadian phase they slept. No other sleep parameters showed steady influence on TEA. The present findings demonstrate that longer period of SWS is associated with the longer sleep time they subjectively experienced during sleep.
authors.affiliation: Department of Psychophysiology, National Institute of Mental Health, National Center of Neurology and Psychiatry,Tokyo, Japan. sayaca@ncnp.go.jp
authors.forename: Sayaka
authors.initials: S
authors.lastname: Aritake-Okada
authors.forename: Makoto
authors.initials: M
authors.lastname: Uchiyama
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Hirokuni
authors.initials: H
authors.lastname: Tagaya
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kuriyama
authors.forename: Masato
authors.initials: M
authors.lastname: Matsuura
authors.forename: Kiyohisa
authors.initials: K
authors.lastname: Takahashi
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Higuchi
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mishima
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D002940:Circadian Rhythm; D006801:Humans; D008297:Male; D017286:Polysomnography / Q000379:methods; D012890:Sleep / Q000502:physiology*; D013998:Time Perception / Q000502:physiology*; D014851:Wakefulness; D055815:Young Adult