"Recovery" function of sleep: effects of purified human interleukin-1 on the sleep and febrile response of cats.

From cats prepared for chronic pollygraphic recording of sleep patterns, records were obtained for 8 hr, after (1) intracerebroventricular (i.c.v.) injection of artificial cerebrospinal fluid (aCSF), day 1; (2) i.c.v. injection of interleukin-1 (Il-1), day 2; and (3) injection of aCSF, day 3. Three doses of Il-1 were tested. The dose of 40 nmol totally inhibited sleep, whereas the dose of 10 nmol slightly prolonged sleep. The dose of 20 nmol of Il-1 elicited sleep and a body temperature increase. Total sleep (TS) time was significantly increased, due mainly to the significant increase in non-REM (NREM) sleep as compared to control day 1. REM sleep was also increased, but this increase did not reach statistical significance. Wakefulness (W) was significantly reduced. At this time cats were febrile. On day 3, a further significant increase in TS occurred. NREM was significantly increased compared with day 1, whereas the increase in REM sleep was significant compared to both day 1 and day 2. At this time body temperature was normal. The increase in REM sleep on days 2 and 3 resulted entirely from the significant increase in the number of REM periods. The results show that Il-1 at a dose of 20 nmol has sleep-promoting effects on NREM and REM sleep concomitant with pyrogenic effects. These two responses differed in their time courses and were not correlated (correlation coefficients were all nonsignificant).