What does long-term sleep deprivation do to your heart?

Consistently sleeping fewer than 6-7 hours increases your risk of a heart attack by approximately 20%. This emerges from several large meta-analyses and cohort studies involving millions of participants. Notably, genetic research does not merely confirm this as a statistical association but as a likely causal relationship: less sleep itself leads to greater cardiac damage. In people who already have coronary artery disease, too little sleep is also linked to a 44-48% higher risk of death, although that last finding comes from observational research.

High blood pressure is a second persistent consequence. People who chronically sleep too little have, on average, a 17% greater chance of developing hypertension. Here too, genetic research points to a causal relationship, not merely coincidence or reverse causality.

How exactly does sleep deprivation damage your heart? Reviews describe multiple pathways operating simultaneously: greater cell damage from oxygen radicals, increased inflammatory activity, disrupted blood clotting, accelerated arterial hardening, and a dysregulated autonomic nervous system that controls heart rate. These mechanisms likely reinforce one another.

An additional warning applies to people who work shifts. They have a 23% higher risk of coronary artery disease. Whether this is entirely due to sleep disruption or also to other aspects of the shift-work system is not yet certain.

More sleep is not necessarily better. A U-shaped relationship consistently emerges: the lowest risk is found at 7-8 hours per night. Long sleep duration (more than 9 hours) is associated with more cardiac problems in observational research, but genetic research finds no causal relationship. Long sleep is probably more often a consequence of pre-existing illness rather than a cause of it. There are also preliminary indications of a higher risk of atrial fibrillation in short sleepers, but that evidence is less robust and is still considered suggestive.