Sleep propensity was assessed in terms of the duration of a spontaneous episode of wakefulness (W). Skin temperatures at six body sites (the abdomen, pectoral region, eye, hand, thigh and foot) were measured (using infrared thermography) during nocturnal polysomnography in 29 9-day-old preterm neonates (postmenstrual age: 209 9 days). Te investigators then determined whether the duration of the W episode depended upon the local skin temperatures measured at the start, during and end of the episode.

Although sleep is of paramount importance for preterm neonates, care of the latter in a neonatal intensive care unit does not favour sleep. Given that several studies in adults have described a 'vegetative preparedness to sleep' (in which distal skin vasodilation before lights-out promotes rapid sleep onset), the investigators looked at whether or not this process operates in preterm neonates. Sleep propensity was assessed in terms of the duration of a spontaneous episode of wakefulness (W). Skin temperatures at six body sites (the abdomen, pectoral region, eye, hand, thigh and foot) were measured (using infrared thermography) during nocturnal polysomnography in 29 9-day-old preterm neonates (postmenstrual age: 209 9 days).

Inclusion Criteria:

• premature newborns 25 to 32 weeks of amenorrhea;
• arrival in the Neonatal Medicine Unit <12 hours of life;
• need for management in a closed incubator;
• availability of an incubator equipped with communication card.

Exclusion Criteria:

• premature newborns> 32 weeks of amenorrhea;
• arrival in the Neonatal Medicine unit after 12 hours of life;
• presence of malformation syndrome or serious heart disease;
• pathology requiring management within the first 10 days of life;
• Apgar score <5 at 10 minutes of life;
• need for initial management in an open incubator;
• unavailability of an incubator equipped with a communication card

Premature infants less than 32 weeks of amenorrhea admitted to birth in the Neonatal Medicine Unit will be included after obtaining written parental consent. Data will be collected during the first 10 days of life of the preterm infant.