Cardiac regulation and depression

Heart rate and heart rate regulation during sleep and wakefulness was studied in 28 patients with major depressive disorder and in 19 control subjects. Heart rate during quiet wakefulness was greater in the depressed group (H.R. = 73.04) than in the control group (H.R. = 65.35) (t = 3.06, p less than 0.005). Heart rate remained elevated throughout sleep in the depressed group as measured in Stage II (H.R. = 67.81) compared with the control group (H.R. = 60.84) (t = 2.49, p less than 0.01). Heart rate increased during movements in sleep in all subjects. The heart rate increases were attenuated in the depressed subjects compared with nondepressed controls (p less than 0.001). The effect was independent of sleep stage or baseline heart rate. All effects were independent of subject age. These findings point to a change in autonomic regulation of heart rate in depression.