title: Increased cerebral blood flow in the right frontal lobe area during sleep precedes self-awakening in humans.
abstract: BACKGROUND
  Some people can subconsciously wake up naturally (self-awakening) at a desired/planned time without external time stimuli. However, the underlying mechanism regulating this ability remains to be elucidated. This study sought to examine the relationship between hemodynamic changes in oxyhemoglobin (oxy-Hb) level in the prefrontal cortex and sleep structures during sleep in subjects instructed to self-awaken.
  
  
  RESULTS
  Fifteen healthy right-handed male volunteers with regular sleep habits participated in a consecutive two-night crossover study. The subjects were instructed to wake up at a specified time ("request" condition) or instructed to sleep until the morning but forced to wake up at 03:00 without prior notice ("surprise" condition). Those who awoke within ± 30 min of the planned waking time were defined as those who succeeded in self-awakening ("success" group). Seven subjects succeeded in self-awakening and eight failed.No significant differences were observed in the amounts of sleep in each stage between conditions or between groups. On the "request" night, an increase in oxy-Hb level in the right prefrontal cortex and a decrease in δ power were observed in the "success" group around 30 min before self-awakening, whereas no such changes were observed in the "failure" group. On the "surprise" night, no significant changes were observed in oxy-Hb level or δ power in either group.
  
  
  CONCLUSIONS
  These findings demonstrate a correlation between self-awakening and a pre-awakening increase in hemodynamic activation in the right prefrontal cortex, suggesting the structure's contribution to time estimation ability.
authors.affiliation: Department of Psychophysiology, National Institute of Mental Health, National Center of Neurology and Psychiatry, Tokyo 187-8502, Japan. sayaca@tokyo-med.ac.jp
authors.forename: Sayaka
authors.initials: S
authors.lastname: Aritake
authors.forename: Shigekazu
authors.initials: S
authors.lastname: Higuchi
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suzuki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Kuriyama
authors.forename: Minori
authors.initials: M
authors.lastname: Enomoto
authors.forename: Takahiro
authors.initials: T
authors.lastname: Soshi
authors.forename: Shingo
authors.initials: S
authors.lastname: Kitamura
authors.forename: Akiko
authors.initials: A
authors.lastname: Hida
authors.forename: Kazuo
authors.initials: K
authors.lastname: Mishima
mesh_terms: D000328:Adult; D018592:Cross-Over Studies; D007839:Functional Laterality; D006801:Humans; D008297:Male; D010108:Oxyhemoglobins / Q000378:metabolism; D017286:Polysomnography / Q000379:methods; D017397:Prefrontal Cortex / Q000098:blood supply* / Q000378:metabolism; D012890:Sleep / Q000502:physiology*; D012894:Sleep Stages / Q000502:physiology; D013997:Time Factors; D014851:Wakefulness / Q000502:physiology*
chemical_list: D010108:Oxyhemoglobins