Poor sleep the night before an experimental stressor predicts reduced NK cell mobilization and slowed recovery in healthy women.

Sleep is important for health; however, poor sleep is a growing problem in many Western societies, particularly among women. Alterations in immune function following poor sleep (defined by duration and disruption) may be linked to ill health. Not yet investigated are the possible effects on stress-induced mobilization of lymphocytes. As natural killer (NK) cells are particularly responsive to acute stress, the present study examined whether sleep period duration and percentage of time awake after sleep onset (WASO) the night before a laboratory stressor would predict reduced NK cell mobilization. Sleep was monitored by actigraphy in 39 healthy women. NK cell peripheral blood numbers were determined at baseline (post-20 min rest), 4 min into a Stroop task, immediately post-task and 30 min after task completion. Participants with high WASO had significantly less NK cell mobilization to the stressor and failed to return to baseline levels after 30 min compared to women with low WASO. No effects were found for sleep period duration. Findings raise the possibility that inadequate NK cell mobilization to, and poor recovery from acute stress may be one pathway by which sleep could impact health.