What is Hypersomnia?

Characteristics of hypersomnia vary from person to person depending on age, lifestyle and other ailments. In extreme cases, a person with hypersomnia might sleep soundly at night for 12 hours or more, but still feel the need to nap during the day. The person's mind remains foggy with drowsiness even after sleeping and napping. It is possible that a person has very disturbed sleep but is not aware of it. Click on the above link to learn more from the Merck Manual Home Edition.