Effects of sleep restriction on subjective and physiological variables in middle-aged Korean adults: an intervention study

Background: Adequate sleep is crucial for normal functioning. However, most people, including middle-aged adults of reproductive age, show a marked reduction in their sleep duration. Thus, sleep is a major issue that should be addressed in health management. We investigated the effects of short-term sleep restriction on subjective parameters (sleepiness, stress, fatigue) and physiological parameters (cortisol, thyrotropin [TSH], thyroxine [T4], triiodothyronine [T3], C-reactive protein [CRP]) in middle-aged adults, the recovery of these parameters after rest, and the associations between parameters. Methods: A total of 118 healthy adults (59 men, 59 women), aged 35–44 years, and without sleep problems, were enrolled. Participants underwent a 4-h sleep restriction per day for 3 day at a hospital, and then returned to their daily lives to take four days of rest. A questionnaire and blood test were administered before and after sleep restriction, and after the recovery period, to assess subjective and physiological parameters. Results: After sleep restriction, sleepiness, fatigue, and stress significantly increased compared to baseline. Cortisol and TSH were elevated after sleep restriction, while T4, T3, and CRP were reduced compared to baseline. After the recovery phase, all parameters were restored to levels similar to baseline levels. Changes in each parameter were mutually associated; fatigue and sleepiness had the strongest association. Conclusion: Our results suggest that even a short period of sleep restriction can have an adverse impact on psychological and physiological stress parameters in middle-aged adults, and that adequate rest and sleep are needed to restore them to normal levels. © 2020