Scientific Investigations
Sleep Misperception in Healthy Adults: Implications for Insomnia Diagnosis
http://dx.doi.org/10.5664/jcsm.2154
Matt T. Bianchi, M.D., Ph.D., M.M.Sc.1,2; Wei Wang, Ph.D.2; Elizabeth B. Klerman, M.D., Ph.D.2
1Sleep Division, Neurology Department, Massachusetts General Hospital, Boston, MA; 2Division of Sleep Medicine, Brigham and Women's Hospital – Harvard Medical School, Boston, MA
Study Objectives:
Time estimation is a complex cognitive task that is especially challenging when the time period includes sleep. To determine the accuracy of sleep duration perception, we investigated 44 healthy subjects participating in multi-day inpatient sleep protocols during which they had extended nighttime and short daytime sleep opportunities but no time cues or knowledge of time of day.
Methods:
The first sleep opportunity was at habitual sleep time and duration. The subsequent 3, 4, or 11 days had 12-h nighttime sleep opportunities and 4-h daytime nap opportunities, potentially creating an experimentally induced “insomnia” with substantial time awake during scheduled sleep.
Results:
Subjective sleep duration estimates were accurate for the first (habitual) sleep opportunity. The subjective reports following nighttime 12-h sleep opportunities significantly underestimated objective sleep duration, while those following daytime 4-h sleep opportunities significantly overestimated objective sleep duration. Misperception errors were not explained by poor sleep efficiency, which was lower during 4-h (~39%) than 12-h opportunities (~71%). Subjective sleep estimates after 4-h opportunities correlated with the percentage of REM and N3 sleep. Subjective sleep estimates following 12-h opportunities were, unexpectedly, negatively correlated with NREM stage 2 sleep.
Conclusion:
The estimation of sleep duration in the absence of time cues may depend on length of sleep opportunity and/or time of day. The results have implications for understanding sleep state misperception, which is an important consideration in patients with insomnia.
Citation:
Bianchi MT; Wang W; Klerman EB. Sleep misperception in healthy adults: implications for insomnia diagnosis. J Clin Sleep Med 2012;8(5):547-554.
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