Short-sleeper

We compared the coping strategies of 39 short-sleepers and 33 longer-sleepers to the stresses associated with the October 17, 1989 San Francisco Bay Area earthquake using their responses to the eight scales of the Ways of Coping Questionnaire.

Source: wiktionary

An insomniac should be differentiated from a short-sleeper, who needs less than 6 hours of sleep per night and has no symptoms or dysfunction.

Source: wiktionary

Habitual short-sleepers did not experience changes in taste perception, activity, or dietary intake following sleep alteration.

Source: wiktionary