The Night Shift: Sleep Blood Pressure and the Strained Heart

Key Takeaway

In a study that followed 5,751 Japanese adults for an average of 9.4 years, an elevated level of BNP, a hormone released by a strained heart, predicted future heart attacks and strokes. Blood pressure measured during sleep appeared to explain a larger share of that danger than daytime home readings, 14.3% versus 5.8%. The figures are not definitive, but they suggest the hours after midnight deserve far more attention than they get.

The Blood Pressure Nobody Checked

Picture a 63-year-old retired schoolteacher at her annual physical. Her office blood pressure is a reassuring 128/78. Her echocardiogram is normal. One blood test comes back mildly high: her BNP sits at 42 pg/mL. Her doctor shrugs. There is no heart failure, so there seems to be nothing to treat. Three years later, she wakes up unable to lift her right arm.

Her chart held dozens of blood pressure readings. Not one was taken while she slept.

BNP, short for B-type natriuretic peptide, is a hormone the heart’s main pumping chamber releases when its walls are stretched under strain. Physicians have used it for decades to diagnose heart…