Sleep restriction suppresses the activity of the hypothalamo-pituitary-adrenal axis but does not affect the autonomic nervous system

Abstract

Sleep restriction is likely to affect the activities of stress axes, namely the hypothalamic-pituitary-adrenal axis (HPA) and the autonomic nervous system (ANS). Sleep restriction is likely to be experienced by everybody, yet the number of studies on that subject is very scarce. The current study aimed to examine the effects of sleep restriction on cortisol awakening response (CAR) as an indicator of HPA and heart rate variability (HRV) as an indicator of ANS activity. Participants (second-year medical students) were divided into two groups as sleep restricting group (n=27, sleeping at 02:00 p.m., waking up at 06:30 a.m.) and normal sleep duration group (n=25, sleeping at 11:00 p.m., waking up at 06:30 a.m.). The participants who filled in sleep dairies provided salivary samples (taken at 0, 15, 30, and 60 min post-awakening) for measurement of CAR and had an electrocardiogram recording (for 5 min) for determination of HRV. Mann-Whitney U test was used for statistical analyses. Sleep restriction reduced cortisol concentrations 15 and 30 minutes following awakening (p0.05). Sleep diaries showed that awakening problem scores were higher but daily disturbed sleep score was lower in the restricted sleep group (p [Med-Science 2022; 11(2.000): 682-9]

Keywords

• sleep
• hpa axis
• cortisol awakening response
• salivary cortisol