Background: Chronic insufficient sleep is a common finding in many pain-related and other medical diseases and is frequently experienced in the general population. Prolonged curtailment of nocturnal sleep has been studied for its adverse effect on cognitive functioning and subjective tiredness, but relatively little is known about its effect on mood and physical symptoms.
Objective: In order to test whether sleep restriction to 50% of the habitual time over 12 days affects diurnal and day-to-day variation of subjective ratings of mood and physical symptoms, 108 adjectives and statements were self-rated using visual analog scales every 2h during the waking period.
Design: Randomized, 16-day controlled in-laboratory study.
Setting: General Clinical Research Center (GCRC).
Participants: Forty healthy subjects aged 21-40 years (14 females, 26 males).
Intervention: Subjects were randomized to either 4h of sleep per night (11 pm-3 am, N=22) or 8h of sleep per night (11 pm-7 am, N=18) for 12 consecutive days.
Main outcome measure: Changes in the factor-derived variables optimism-sociability, tiredness-fatigue, anger-aggression, bodily discomfort, and items constituting bodily discomfort were compared between groups.
Results: Optimism-sociability progressively declined over consecutive days of sleep restriction by 15%. Bodily discomfort showed a slight, but significant interindividual increase of 3% across days of sleep restriction due to significant increases of generalized body pain, back pain, and stomach pain. Optimism-sociability and tiredness-fatigue showed diurnal variations with a quadratic function period within each day in both conditions.
Conclusion: The data suggest that chronic insufficient sleep may contribute to the onset and amplification of pain and affect health by compromising optimistic outlook and psychosocial functioning.