Quantitative analysis of short term deprivation and recovery of desynchronized sleep in cats

A quantitative analysis of desynchronized sleep (DS) deprivation (exposure to low ambient temperature) and recovery was carried out in unrestrained cats. The results show that: (1) the circadian obligate quota of DS is precisely regulated by a control mechanism paying by the 24th h the DS debt induced by up to 14 h of total DS deprivation, if recovery occurs during the rest phase of circadian photoperiodicity (CP); (2) during static rebound DS hourly duration is increased by 40 +/- 4 sec/h of total deprivation (mean and S.E.) and there is a statistically significant increase in the hourly frequency and in the duration of DS episodes, with respect to control values; (3) the hourly obligate and facultative quotas of DS amount to 409 +/- 82 and 229 +/- 140 sec/h (mean and S.D.), respectively. (4) preoptic heating during deprivation at low ambient temperature decreases the DS static rebound during recovery at control ambient temperature by an amount corresponding to the cumulative duration of DS episodes elicited by the preoptic treatment; (5) preoptic temperature decreases the more markedly the shorter the duration of exposure to low ambient temperature and regains control values the sooner the smaller the DS debt incurred during deprivation; (6) DS debt cumulation is a continuous process which develops at a steady rate during day and night, whereas DS debt payment is a discontinuous process (ultradian rhythm of DS) which develops at a variable rate depending on the DS debt and on the phase of CP.