1. Natural short sleeper  (Trust Mark: Doctor-Reviewed)
A natural short sleeper is someone who sleeps a lot less in a 24-hour period than is expected for other people of the same age. The person is not excessively sleepy. • Reviewer: Allen J. Blaivas, DO, Pulmonary, Critical Care, and Sleep Medicine, Department of Veteran Affairs, VA System, East Orange, NY. Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

2. Sleep disorders  (Trust Mark: Doctor-Reviewed)
Sleep disorders involve any difficulties related to sleeping, including difficulty falling or staying asleep, falling asleep at inappropriate times, excessive total sleep time, or abnormal behaviors associated with sleep.• Reviewer: Allen J. Blaivas, DO, Pulmonary, Critical Care, and Sleep Medicine, Department of Veteran Affairs, VA New Jersey Health Care System, East Orange, NJ . Review provided by VeriMed Healthcare Network. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.