Vol. 279, Issue 6, R1980-R1987, December 2000
Attenuation of sleep propensity, core hypothermia, and
peripheral heat loss after temazepam tolerance
Saul S.
Gilbert1,
Helen
J.
Burgess1,
David J.
Kennaway2, and
Drew
Dawson1
1 Centre for Sleep Research, The University of South
Australia, The Queen Elizabeth Hospital, Woodville, South Australia
5011; and 2 Department of Obstetrics and Gynaecology, The
University of Adelaide, Adelaide, South Australia 5005, Australia
If changes in thermoregulation
mediate sleepiness induced by sedative/hypnotics, then a reduction in
the soporific efficacy (tolerance) of these agents may be accompanied
by a concomitant reduction in their thermoregulatory effects. We
compared the thermoregulatory and soporific effects of acute temazepam
(30 mg at 1400) in 11 young male subjects before and immediately after
7 consecutive days of temazepam (30 mg). Subjects lay supine
(0800-2030), while foot (Tft) and rectal
(Tc) temperatures were recorded. Sleep onset latency (SOL)
was measured hourly using 20-min multiple sleep latency tests. Relative
to placebo, temazepam significantly reduced both Tc and SOL
(
0.31°C and 14.1 min) while increasing Tft (3.39°C). A significant tolerance developed after the week of temazepam, with a
mean reduction in soporific efficacy of 4.0 ± 0.8 min. This was
accompanied by a concomitant attenuation in both Tc
(0.16°C) and Tft (1.44°C). Furthermore, SOL was
temporally related to Tft and the maximum rate of decline
in Tc before and after tolerance. Together, these results
indicate that the thermoregulatory system may be functionally involved
in the regulation of sleepiness.
heart rate; multiple sleep latency test; human male
