Studies have shown that people who say they sleep less than six hours or more then 8 hours have higher amounts of adverse health outcomes like cardiovascular disease, diabetes, and obesity. But studies that actually measure how long someone sleeps have not shown an association of documented longer sleep times and adverse health. And few studies have looked at potential abnormalities in self reported long sleepers.
Dr. Patel and others analyzed subjective and objective sleep data from older (at least 65 years old) men that were part of a larger study on osteoporosis, and the results are published in the May edition of the Sleep Journal. The researchers compared data from men who were classified as long vs normal duration sleepers. Sleep duration was defined as normal if the men said they slept 7-8 hours per night and long if they slept 9 or more hours per night. The results showed that self reported long sleepers were older, more likely to have diabetes, and the have worse cognitive functioning. There was a trend (but it did not reach statistical significance) showing more cardiovascular disease and depression in the self-reported long sleepers. In fact, antidepressant use was twice that in the self reported normal sleep duration group. There was no difference in smoking rates, alcohol use, caffeine intake, sedative use, or pain medicine use between the two groups.
As you might expect, the self reported long sleepers actually did sleep longer than the men who reported they slept normal amounts. On average, the long sleepers slept 20-43 minutes more than normal duration sleepers, depending on the way sleep was measured. Also, self-reported long sleepers tended to overestimate their sleep duration to a greater extent than self-reported normal sleepers. In other words, these men did sleep longer than normal sleepers, but not as long as they thought they were sleeping. Sleep quality, sleep stages, and daytime sleepiness was not different between the two groups either. Finally, there was no difference in the rates of sleep disordered breathing (like sleep apnea), periodic limb movement disorder (similar to restless legs syndrome), or awakenings at night between the two groups.
Bottom line: Those who report sleeping longer do in fact sleep longer, but it does not appear to be caused by a sleep abnormality or other health characteristic.