National Sleep Foundation

Chapter 4: Primary Hypersomnias

Assessment and Diagnosis

Problems in school and with conduct are often the first clues to Behaviorally-induced ISS.11  It is the first consideration when a patient of any age presents with EDS. Assessing sleep history and current sleep habits (e.g., by using a sleep log or wrist actigraph) can help determine if the patient’s habitual sleep times are shorter than expected from age-adjusted norms.

Behaviorally-induced ISS is often difficult to diagnose in patients who have an inherent above-average sleep need, such as long sleepers, since their sleep pattern may falsely appear to fall within the normal range. The presence of excessive sleep times on weekends, or in other situations when habitual sleep times are not maintained, can help diagnose such patients.

Another approach to assess patients who are difficult to diagnose is to prescribe a two-week trial period during which the amount of time he or she spends in bed is systematically increased by one to two hours per night, and documented by either a wrist actigraph or sleep log. A dramatic improvement in levels of EDS after the two-week trial suggests the presence of Behaviorally-induced ISS. If EDS remains, however, another EDS-associated hypersomnia should be considered.12


  1. Partinen M, Hublin C. “Epidemiology of Sleep Disorders,” Kryger M, Roth T, Dement W (ed.), Principles and Practice of Sleep Medicine (5th Edition), St. Louis: Elsevier Saunders, 2011, pp. 694-715.
  2. Personal communication (Peter Hauri, MD, June 2006)