Problems that could stem from too much, or less sleep, includes depression, heart disease, diabetes and other underlying health concerns.

According to the analysis by Professor Franco Cappuccio, 30% more of the long sleepers died compared to medium sleepers, while 12% more of short sleepers died in the same period compared to medium sleepers. And it turns out that the significant rise in mortality risk is equivalent to the risk of drinking several units of alcohol per day.
Prof Cappuccio said, "Naturally, you have to rely on your memory and you don’t know if you’re reporting time in bed or time asleep and whether you’re accounting for naps, and so forth."
Source-ANI