Sleep in Infants with Down Syndrome or Familial Likelihood of Autism in the First Year of Life.

Sleep problems have been associated with atypical development, but there is limited understanding of when sleep problems arise and how they differ across clinical populations. We aimed to evaluate sleep characteristics of infants with Down syndrome (DS), higher familial likelihood of autism (HL) and lower familial likelihood of autism (LL) at 6 and 12 months of age. Participants were from two longitudinal, multi-site, studies. Sleep was estimated by parent report on the Brief Infant Sleep Questionnaire at 6 months (59 DS, 173 HL, 54 LL); 12 months (58 DS, 129 HL, 30 LL); and in a longitudinal subset at both 6 and 12 months (100 HL; 23 LL; 33 DS). At 6-months, DS parents reported less concern about infant sleep and less night wakefulness than LL parents; HL parents reported longer sleep onset latency (SOL). At 12 months DS parents reported less night sleep and more night wakefulness; HL parents reported less night sleep, more night wakefulness and longer SOL compared to LL. Night wakefulness increased significantly in the DS and HL groups from 6 to 12 months of age. A higher proportion of DS and HL infants decreased Night Sleep and increased Night Wakefulness compared with the LL group. A higher proportion of DS infants increased SOL compared with the LL group. Sleep alterations are present in the first year of life and may differ in DS and HL infants. The mechanisms behind these sleep alterations may be an important early intervention target.