night-owl insomnia

delayed sleep phase syndrome

A sleep disorder characterised by the inability to fall asleep for several hours after going to bed. Often related to abuse of alcohol or sleeping pills, the condition may respond to bright light therapy administered several hours before bedtime.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.

night-owl insomnia

Delayed sleep phase syndrome, see there.
McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.