Total Sleep Deprivation Induces an Acute and Transient Increase in NK Cell Activity in Healthy Young Volunteers

STUDY OBJECTIVESTo investigate the effects of one night's total sleep deprivation (TSD) on NK cell activity, with rigorous control of circadian phase of sampling points as well as physical exercise level in association with sleep deprivation.DESIGNThe mean sleep onset time of each subject before starting the study was defined as his 0000 h. This study was composed of a Sleep-Sleep session (sleep times, 00:00 h - 08:00 h and 24:00 h - 32:00 h) and a Sleep-Wake session (sleep time, 00:00 h - 08:00 h) with TSD (24:00 h - 32:00 h) placed in a cross-over design with 2-week interval between each session. In each session, the subjects were rested in the supine position under dim light from - 06:00 h to 36:00 h (for 42 hours).SETTINGUniversity-based sleep and chronobiology laboratoryPARTICIPANTS10 healthy adult men (mean age, 20.9 y; age range, 19-23 y)INTERVENTIONSNA.MEASUREMENTS AND RESULTSNK cell activity was measured every 4 hours from 12:00 h. NK cell activity during TSD (at 28:00 h) has been revealed to significantly increase (p=0.01) compared with the corresponding value in the Sleep-Sleep session. This effect was weaker at their usual waking time 32:00 h (p=0.07), and disappeared until 36:00 h (4 hours after awakening). The circadian rhythm phases (dim light melatonin onset time) were coincident between the 2 sessions.CONCLUSIONSThe present findings suggest that one night TSD induces an acute and transient increase in NK cell activity that is not influenced by the effects of circadian rhythm or the amount of physical exercise undertaken during TSD.