title: [Amount of sleep and changes in its patterns in children less than two years old].
abstract: OBJECTIVE
  The aim is to study the sleep duration and the 24-hour sleep distribution pattern in children under 2 years-old from two different areas of Spain, as well as to determine the prevalence of abnormal sleep duration and the influence of age on this prevalence, and compare them with the already published data.
  
  
  METHODS
  An observational, descriptive and cross-sectional study on children from two health centers: one in Castilla y León and the other in Asturias. Their parents completed the Brief Infant Sleep Questionnaire (BISQ). Daytime and nighttime sleep duration was assessed, with percentiles being used to evaluate the results. Two groups were created: one according to the age (children under or above 6 months), and the other according to the area.
  
  
  RESULTS
  A total of 125 children were studied (73 males). The nighttime sleep duration increased from 8.28±2.06 hours to 10.43±1.21 hours (P=.0001) and the daytime sleep decreased from 4.61±2.66 to 1.96±0.79 hours (P=.0001) for children under 6 months and above 6 months, respectively. The children from Castilla y León slept more during daytime than those from Asturias (3.91±2.67 vs 3.00±2.09 hours, P=.041). Nineteen children had a total sleep duration below the 2nd percentile. A sleep duration below normal percentiles was observed in children under 6 months (14/72 vs 5/53, P=.006).
  
  
  CONCLUSIONS
  As children grow older, they substitute daytime sleep for nighttime sleep. Approximately 15% of the children under 2 years-old may have changes in sleep duration, and is more common in children under 6 months.
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España. Electronic address: mfmiaja@gmail.com.
authors.forename: M
authors.initials: M
authors.lastname: Fernández Miaja
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España.
authors.forename: C
authors.initials: C
authors.lastname: Rodríguez Fernández
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España.
authors.forename: M L
authors.initials: ML
authors.lastname: Fernández Pérez
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España.
authors.forename: D
authors.initials: D
authors.lastname: Mata Zubillaga
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España.
authors.forename: J
authors.initials: J
authors.lastname: Miaja Quiñones
authors.affiliation: Servicio de Pediatría. Complejo Asistencial Universitario de León (CAULE), León, España.
authors.forename: L M
authors.initials: LM
authors.lastname: Rodríguez Fernández
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D012890:Sleep / Q000502:physiology; D013997:Time Factors
keywords: Brief Infant Sleep Questionnaire; Daytime sleep; Duración del sueño; Nighttime sleep; Percentiles de duración del sueño; Sleep duration; Sleep duration percentiles; Sueño diurno; Sueño nocturno