1. Shimada, Mieko PhD
  2. Segawa, Masaya MD
  3. Higurashi, Makoto MD
  4. Kimura, Rumiko PhD
  5. Oku, Kikuko MD
  6. Yamanami, Sadao MD
  7. Akamatsu, Hiroshi MD


The influence of phototherapy treatment during the neonatal period on sleep-wake rhythm, and its long-term effects on biological rhythms, was evaluated in preterm and full-term infants. Forty-three infants treated with phototherapy during the neonatal period and 47 untreated infants were examined for entrainment of sleep-wake rhythms between 16 and 52 weeks and for sleep-wake and saliva cortisol rhythms at 2.5 years of age. The age of sleep-wake rhythm entrainment was not significantly different between the 2 groups. No correlations between duration of exposure to phototherapy and corrected age of entrainment of sleep-wake rhythm were observed. At follow-up, no significant differences in sleep-wake and saliva cortisol rhythms were observed between the 2 groups, indicating that circadian variations were similar to those in adults.