EFFECTS OF INSUFFICIENT SLEEP ON BLED PRESSURE MONITORED BY A NEW MULTIBIOMEDICAL RECORDER

Blood pressure varies in relation to factors such as physical activity , body position, ambient temperature, and autonomic nervous system act ivity. Therefore, we have developed a portable multibiomedical (PMB) r ecorder that monitors five parameters: indirect blood pressure; physic al activity, body position, ambient temperature, and RR interval of th e electrocardiogram. In the present study, we applied the PMB recorder over a 24-hour period to study the effect of insufficient sleep on bl ood pressure in subjects doing extensive overtime work. The parameters listed above were measured by the PMB recorder throughout a normal wo rkday (mean period of sleep, 8 hours) and throughout a day with insuff icient sleep (mean period of sleep, 3.6 hours) in 18 male technical wo rkers aged 13 to 48 years old. Blood pressure (mean systolic/diastolic pressure+/-SD) significantly increased the day after a sleep-insuffic ient night (129+/-8/79+/-6 mm Hg) compared with the day after a normal night (123+/-8/76+/-7 mm Hg, P<.05). However, ambient temperature, me an number of steps per minute, and percentage of time spent in a stand ing position showed no significant difference between these days. Spec tral analysis of RR intervals showed that the ratio of the low-frequen cy component on the RR power spectrum (0.05 to 0.15 Hz) to the high-fr equency component (0.15 to 0.40 Hz) was higher on the sleep-insufficie nt day (2.17+/-0.37 versus 1.81+/-0.37), as was the urinary excretion of norepinephrine (P<.05). Heart rate was significantly higher on The sleep-insufficient day (81+/-11 versus 76+/-8 brats per minute), after the data of two subjects with abnormal levels of physical activity we re excluded (P<.01). These data suggest that lack of sleep may increas e sympathetic nervous system activity on the following day, leading to increased blood pressure. The PMB recorder was useful for precisely e valuating the relationship bei seen blood pressure and environmental f actors.