Source: Sleep  |  Posted 9 years ago

Sedative-hypnotics may lead to changes in body temperature but the promotion of sleep appears to vary between agents.

Previous research suggested that there was an association between the sleep-promoting effects of the sedative-hypnotics such as melatonin and temazepam and a fall in core body temperature.

In this study, scientists at the Centre for Sleep Research, University of South Australia in Woodville investigated whether alterations in body temperature were a general feature of these drugs. In addition, melatonin and zopiclone were compared to determine sleep inducing, core and peripheral temperature effects.

In a double-blind, crossover design, 12 patients (seven males, five females, average age 20.3 years) were given melatonin (5mg), zopiclone (Imovane (TM); 7.5 mg) or a placebo 14.00 hours. The had been supine from 08.00 to 21.30 hours, in single, light and temperature controlled rooms.

Modified hourly multiple sleep onset latency tests (MSLT) were conducted, lasting 20 minutes, heart rate was recorded from 11.00 to 20.00 hours. In addition, core body (Tc) and foot temperature (TFt) underwent continuous recording with thermistors.

There was a considerably reduced sleep onset with melatonin and zopiclone compared to placebo. Core body temperature declined for melatonin due to increased loss of peripheral heat, but increased in foot temperature. The researchers also suggested a possible reduction in peripheral heat loss was indicated by a decreased heart rate.

An increased heat loss in foot temperature following zopiclone administration was reported, but no cardiac effects. A negative association was noted for melatonin between TC but it was only weak for zopiclone, say the researchers.