Definition of Natural short sleeper:

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.

Causes, incidence, and risk factors:

Although the individual need for sleep varies quite a bit, the typical adult requires an average of 7 - 10 hours of sleep each night. Short sleepers sleep less than 75% of what is normal for their age, and wake up spontaneously.

Natural short sleepers are different from people who chronically do not get enough sleep because of work or family demands, or who have medical conditions that disrupt sleep.