The relationship between sleep deprivation and the nocturnal decline of blood pressure

Abstract

Blood pressure (BP) has a circadian pattern with a 10% to 15% drop in systolic and diastolic BP comparing nighttime and daytime averages. The mechanism and the "reason" for the decline of nocturnal blood pressure has not been described. If the nocturnal decline is a restorative physiologic process we reasoned that sleep deprivation would increase the nocturnal drop. Thus, we tested the hypothesis that there is a compensatory decline in nocturnal sleep blood pressure after a period of nocturnal sleep deprivation. Twenty-four house staff personnel (normotensive and not taking any BP medications) with a mean age of 29.3 years were recruited for this study (13 men and 11 women). Subjects were randomly assigned to have 24-h BP monitoring after being sleep deprived (on call with 3 +/- 1.3 h of sleep) or after a normal night's sleep (7.3 +/- 0.8 h). There was no significant difference in hours asleep or time to bed or time awake for both 24-h studies. Subjects had similar activities for both monitoring intervals. The percent change in day awake versus night asleep mean values for systolic BP, diastolic BP, and mean arterial pressure for sleep deprived and normal night's sleep intervals were compared using paired t tests. None of these paired parameters were significantly different despite a subjectively "deeper" sleep postcall. In conclusion, sleep deprivation does not appear to result in a compensatory decline in nocturnal blood pressure. Thus, the "reason" for the normal nocturnal decline in blood pressure remains to be explored.