1. ¹Institute of Internal Medicine, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia
2. ²Research Institute for Molecular Biology and Biophysics, Siberian Branch of the Russian Academy of Medical Sciences, Novosibirsk, Russia

Correspondence: Dr KV Danilenko, Institute of Internal Medicine SB RAMS, Bogatkova 175/1, Novosibirsk 630089, Russia. Tel: +7 3832 679755; Fax: +7 3832 642516; E-mail: dani@irs.ru

Received 30 September 2004; Revised 28 December 2004; Accepted 7 January 2005; Published online 16 February 2005.

Abstract

Patients with winter depression (seasonal affective disorder (SAD)) commonly complain of sleepiness. Sleepiness can be objectively measured by spectral analysis of the waking electroencephalogram (EEG) in the 1–10 Hz band. The waking EEG was measured every 3 h in 16 female SAD patients and 13 age-matched control women throughout a total sleep deprivation of 30 h. Melatonin (or placebo) under double-blind conditions was administered subsequently (0.5 mg at 1700 h for 6 days), appropriately timed to phase advance circadian rhythms, followed by reassessment in the laboratory for 12 h. The increase in EEG power density in a narrow theta band (5–5.99 Hz, derivation Fz–Cz) during the 30 h protocol was significantly attenuated in patients compared with controls (difference between linear trends p=0.037). Sleepiness (p=0.092) and energy (p=0.045) self-ratings followed a similar pattern. Six patients improved after sleep deprivation (50% reduction on SIGH-SAD₂₂ score). EEG power density dynamics was correlated with clinical response to sleep deprivation: the steeper the build-up (as in controls), the better the improvement (p<0.05). There was no differential effect of melatonin or placebo on any measure; both treatments stabilized the improvement. Overall, patients with winter depression manifest similar wake EEG characteristics as long sleepers or late chronotype with respect to an insufficient build-up of homeostatic sleep pressure. Sleep deprivation was an effective antidepressant treatment for some patients, but evening melatonin was not more efficacious than placebo in sustaining this antidepressant effect.