Vigilance performance of men sleeping under arctic conditions.

This study investigated the effect of cold exposure on vigilance performance in men working and sleeping under Arctic conditions. The results were compared with changes in the amount of REM sleep. EEG sleep recordings were made on six subjects during five baseline nights in laboratory conditions, 16 experimental nights in Arctic conditions, and four recovery nights in the laboratory. Vigilance tests were administered every second day during the experimental period and two times during each of the baseline and recovery periods. During the first night in the Arctic, the amount of REM sleep fell to 50% of baseline and a large decrement occurred in detection performance on the following morning. During the remaining nights in the cold, REM deprivation averaged about 25% with somewhat greater deprivation occurring during colder nights. Reaction time measures generally increased throughout the experimental period and subsequently showed incomplete recovery. However, detection performance gradually improved during the experimental period but showed some regression following colder-than-usual nights, when REM deprivation increased. This suggested that performance on this type of task may be related to temperature variations and changes in REM deprivation.