The relationship between sleep and disease suggests that there exists a connection between the brain and the body that extends beyond merely influencing the brain itself.

Among brain-related disorders, short sleep was significantly associated with depressive episodes and anxiety disorders, as seen in other studies of sleep and mental health. Short sleep was also associated with obesity, type 2 diabetes, hypertension, ischemic heart disease, and heart arrhythmias.

Short and long sleep were associated with chronic obstructive pulmonary disease, asthma, and a cluster of digestive disorders, including gastritis and gastroesophageal reflux disease.