Local sweating responses during recovery sleep after sleep deprivation in humans

Changes in the central control of sweating were investigated in five sleep-deprived subjects (kept awake for 40 h) during their recovery sleep under warm ambient conditions [operative temperature (T_o) was either 35 or 38° C]. Oesophageal (T_oes) and mean skin (T_sk) temperatures, chest sweat rate (m_sw,ch), and concomitant electro-encephalographic data were recorded. Throughout the night at 35 or 38° C T_o, m_sw,ch changes were measured at a constant local chest skin temperature (T_ch) of 35.5° C. The results showed that body temperatures (T_oes and T_sk) of sleep-deprived subjects were influenced by thermal and hypnogogic conditions. The m_sw,ch levels correlated positively with T_oes in the subjects studied during sleep stage 1–2 (light sleep: LS), sleep stage 3–4 (slow wave sleep: SWS) and rapid eye movement (REM) sleep. Contrary to what has been reported in normal sleep, firstly, the T_oes threshold for sweating onset differed between REM sleep and both LS and SWS, and, secondly, the slopes of the m_sw,ch versus T_oes relationships were unchanged between REM and non-REM (i.e. LS or SWS) sleep. The changes observed after sleep deprivation were hypothesized to be due to alterations in the functioning of the central nervous system controller.