The objective of this study was to explore the possibility of using distal–proximal skin temperature gradient (DPG) to predict sleep-onset latency of night-time sleep for infants at home.Methods:
Foot (for distal) and abdominal (for proximal) skin temperature during sleep onset in healthy infants, aged 4–9 months, was continuously recorded using a temperature logger at home. Sleep-onset latency during each study night was defined as the interval from lights-off to sleep onset, determined on actigraphy. Association of DPG profile after lights-off with sleep-onset latency on the study nights was evaluated.Results:
Data for 43 nights from 28 infants were available for analysis. With regard to low DPG (<−2.5°C) at lights-off, >60% of infants fell asleep within 30 min if DPG was increased to ≥−2.5°C within 15 min after lights-off. If DPG remained at <−2.5°C at 15 min after lights-off, however, only 20% of infants fell asleep within 30 min. In addition, if infants were still awake at 15 min after lights-off and the DPG at that time was <−2.5°C, they were not likely to quickly fall asleep (predictive value was 0.875).Conclusions:
Increase in DPG by 15 min after lights-off is a key determinant for sleep-onset latency.