Effect of sleep on blood pressure and its correlates.

The aim of the present study was to investigate changes in blood pressure, heart rate, renal plasma flow, catecholamines, renin and angiotensin in fifteen patients with uncomplicated essential hypertension. During sleep a progressive fall in blood pressure and heart rate was found. Renal plasma flow and calculated renal vascular resistance were reduced as well. Noradrenaline and adrenaline decreased, but renin and angiotensin rose. The rise in renin was inversely related to age. Blood pressure was more variable during REM-sleep but otherwise there were no differences in the level of blood pressure and catecholamines during REM-sleep or during sleep stage IV.