Sleep restriction progress to cardiac autonomic imbalance
Previous studies have shown that night shift work is thought to be a risk factor for cardiovascular disease and inadequate sleep is a common feature of night shift work. Since it’s more difficult to maintain adequate sleep duration among night watchmen during their working schedule, hence the purpose of our present study was to investigate whether mental stress or fatigue over restricted sleep period in night shift, affects HRV, in order to elucidate on cardiac autonomic modulation among nigh watchmen. With the purpose of this, autonomic activity determined from the levels of the heart rate variability (HRV), and also measured, body mass index (BMI), body fat percentage from skin fold thickness (biceps, triceps, and sub-scapular, supra-iliac) among normal sleep watchmen) (n = 28) and restricted sleep watchmen (n = 28) at first (1st) day, fourth (4th) day and seventh (7th) day of restricted sleep period. We observed that among restricted sleep individuals, sleepiness was significant increase at 4th day and 7th day when compare to normal sleep individuals, and, there was significant increase in, mean NN, VLF, LF, LF(nu), LF/ HF AND significant decrease in SDNN, RMSSD, TSP, HF, and HF(nu) at 4th and 7th day of restricted sleep period. In addition to, this variable was more significant increase on 7th day, when compare with 4th day. As well as there was significant negative correlation between LF(nu) and HF(nu) at subsequent 4th day [r (48) = 0.84; P = 0.01] and 7th day[r (48) = -0.95; P = 0.01] of restricted sleep period. However we didn’t observe any significant variation in BMI, and body fat percentage among restricted sleep individuals when compare to normal sleep individuals with in this restricted sleep periods. Hence we concluded that partial sleep loss may cause autonomic imbalance represented by increased sympathetic and decreased parasympathetic activity; as revealed by altered HRV indices observed in this study.
Keywords: Sleep restriction, Autonomic balance, BMI, HRV