title: Does the transition into daylight saving time really cause partial sleep deprivation?
abstract: OBJECTIVE
  To identify possible changes in the sleep patterns according to chronotype in undergraduate students during the daylight saving time (DST) transition.
  
  
  METHODS
  A total of 378 students answered the Morningness-Eveningness Questionnaire (MEQ) to determine their chronotype and kept a diary about sleep-wake schedules 1 week before and after the DST transition. Oral mucosal cell samples were collected for genetic analysis.
  
  
  RESULTS
  After the DST transition, intermediate types (I-types) delayed bedtime and increased their time in bed and all groups delayed their wake-up time. All groups presented a shorter phase angle between sunset and the bedtime after the DST transition. On the other hand, only E-types showed a tendency to reduce the phase angle between sunrise and wake-up time, while I-types and M-types kept the same phase angles between sunrise and wake-up time after the DST transition. The polymorphisms in the human genes CLOCK and PER3 were not associated with individual differences in sleep patterns, nor were they associated with an adjustment to the DST transition.
  
  
  CONCLUSIONS
  Under the new set of social times determined by DST, the adjustment was only partial. I-types delayed bedtime and all groups delayed their wake-up times after the beginning of DST. Consequently, the time in bed after the DST transition was not reduced; Morning (M-types) and Evening-types (E-types) kept the same time in bed and I-types showed an increase on it.
authors.affiliation: Departmento of Cell Biology and.
authors.forename: Manoel Carlos
authors.initials: MC
authors.lastname: Toth Quintilham
authors.forename: Taísa
authors.initials: T
authors.lastname: Adamowicz
authors.forename: Erico Felden
authors.initials: EF
authors.lastname: Pereira
authors.forename: Mario
authors.initials: M
authors.lastname: Pedrazzoli
authors.forename: Fernando Mazzilli
authors.initials: FM
authors.lastname: Louzada
mesh_terms: D000328:Adult; D056926:CLOCK Proteins; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D056950:Period Circadian Proteins; D017440:Photoperiod; D020641:Polymorphism, Single Nucleotide; D012892:Sleep Deprivation / Q000235:genetics / Q000503:physiopathology*; D013334:Students; D013995:Time; D014495:Universities
chemical_list: C512644:PER3 protein, human; D056950:Period Circadian Proteins; D056926:CLOCK Proteins; C538943:CLOCK protein, human
keywords: Chronotype; clock genes; daylight saving time; sleep–wake cycle