ABSTRACT
Chronic fatigue syndrome occurring in previously healthy children and adolescents is one of the most vexing problems encountered by pediatric practitioners. To investigate the biological rhythms in the pediatric patients with CFS, we examined sleep pattern, circadian rhythm of core body temperature (CBT), and plasma cortisol in 41 patients, aged between 10 and 19 years, who did not have any physical or psychiatric disorders, but had non-specific complaints, and were suspected to have a circadian rhythm disturbance. They were diagnosed as having CFS on the basis of published criteria. Circadian variation of CBT in the CFS patients did not present a clear rhythm, and appearance time of their lowest CBT was significantly delayed compared to healthy subjects. Amplitude of circadian CBT changes, fitted to a cosinor curve by the least square method, was significantly smaller in the patients than in healthy subjects. Moreover, circadian rhythm of plasma cortisol in the patients appeared to be quite different, compared to healthy subjects. These findings suggest that their clinical psychosomatic symptoms (e.g., fatigue and sleep disturbance) might be closely related to the desynchronization of their biorhythms, particularly the circadian rhythm of body temperature and cortisol rhythm.