Dynamics of electroencephalographic slow wave activity and body temperature during monophasic and biphasic human sleep

Dynamics of electroencephalographic (EEG) slow wave activity (0.5-4.5 Hz) a nd body temperature, as estimates, respectively, of the process S and proce ss C, regulating sleep and waking alternate occurrence, were measured durin g monophasic and biphasic sleep patterns that occurred spontaneously in a 3 5-year-old woman who lived for 105 days in a winter-type photoperiod (10-14 h light-dark). In monophasic nights, rate of EEG synchronization showed a decreasing trend across the first three non-rapid eye movement (NREM) perio ds. In biphasic nights, rate of EEG synchronization increased during the th ird NREM period which precedes the nocturnal awakening. Temperature cycle w as not different between biphasic and monophasic nights. Those results conf irm that EEG dynamics reflects homeostatic sleep regulatory mechanism, and suggest that the period of prolonged wakefulness in the middle of biphasic night is preprogrammed. (C) 2001 Elsevier Science Ireland Ltd. All rights r eserved.