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J Affect Disord. 2002 May;69(1-3):231-6.

Is dawn simulation effective in ameliorating the difficulty awakening in seasonal affective disorder associated with hypersomnia?

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University of Washington School of Medicine, Department of Psychiatry and Behavioral Sciences, Harborview Medical Center, 325 Ninth Avenue, Seattle, WA 98104, USA.



Patients with winter depression, (seasonal affective disorder, SAD) frequently complain of difficulty awakening in the morning. Dawn simulation has been found effective in treating SAD, but its effect on difficulty awakening has not been assessed.


Fifty medication-free patients with SAD associated with hypersomnia were randomized to receive either 1 week of dawn simulation (250 lux) or a dim (0.2-2 lux) placebo signal. The patients assessed their level of drowsiness upon awakening during the baseline week and during the treatment week using the Stanford sleepiness scale (SSS). A psychiatrist rated difficulty awakening after the baseline week and after the treatment week.


Dawn simulation lowered both the difficulty awakening score (P<0.05) and the SSS score (P<0.05) compared to the placebo dawn signal.


Replication is necessary. No biological markers of circadian phase were measured.


Compared to a placebo condition, dawn simulation appears effective in decreasing both prospectively assessed morning drowsiness and retrospectively assessed difficulty awakening. The symptom of difficulty awakening is consistent with the phase delay hypothesis of SAD. Assessment of difficulty awakening could prove useful in the evaluation of SAD.

[Indexed for MEDLINE]

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