[Effects of intermittent wakening on sleep pattern of nighttime caregiver: an EEG study with a single subject].

In order to investigate the effects of night wakening on sleep pattern of caregiver, a woman aged 45 years was studied using electroencephalogram (EEG). After two adaptation nights, her all-night EEG readings were recorded for six nights. During the first three consecutive nights, the subject slept by the side of a patient at a private ward of hospital and wakened by herself several times a night to provide care for the patient (care nights). Of the later three nights, her sleep EEGs were recorded at her home (free nights). The first free night was following three care nights and the other two free nights were after 2 weeks. The results were summarized as follows; 1) Sleep period time (SPT) of care nights differed in different nights. In contrast to the SPT range of 356-367 min during free nights, it was 271-391 min during the care nights. 2) The rhythm of sleep cycles of care nights was not stable, though the subject wakened by herself, not using an alarm clock. 3) Although there were few changes occurring in sleep efficiency (SE) and percent each stage for SPT (%SPT) between the first and second care night, SE of the third care night was more similar to SE of free nights than SE of the first two care nights, and so was %SPT of the third care night. 4) Sleep latency (SL) decreased during the four consecutive nights, i.e. the three care nights and the first free night, and SL of the third care night and the first free night were shorter than SL of the last two free nights. The accumulation of fatigue and stress of nighttime care was suggested.