WebMD says “reclining for long periods of time with your legs elevated can cause blood to pool in your legs, increasing the risk of blood clots. Blood clots can then travel to your lungs, heart, or brain and cause a sudden blockage of blood vessels, resulting in a heart attack or stroke.
A recent study of more than 60,000 people found that those who slept in a recliner were more than twice as likely to develop deep vein thrombosis (DVT) as those who slept on a bed.