Band-specific electroencephalogram and brain cooling abnormalities during NREM sleep in patients with winter depression.
BACKGROUND
We previously reported that delta wave activity and facial skin temperatures, an index of brain cooling activity, were both abnormal during sleep in patients with winter depression (SAD). Because other electroencephalographic (EEG) frequencies may also convey relevant thermal, homeostatic, and circadian information, we sought to spectrally analyze delta, theta, alpha, and sigma frequencies during sleep from 23 patients with SAD and 23 healthy control subjects.


METHODS
We computed means for delta, theta, alpha, and sigma power during both NREM and REM sleep. We also generated 22 cross-correlation functions for each group by crossing facial and rectal temperature with each other, as well as with delta, theta, alpha, and sigma frequencies.


RESULTS
We found that delta, theta, and alpha frequency activities were all increased during NREM, but not REM sleep, in patients with SAD. In addition, there were significant and abnormal cross-correlations between facial temperatures and delta and theta frequencies during NREM sleep in patients with SAD.


CONCLUSIONS
Patients with winter depression exhibit correlated abnormalities of sleep homeostasis and brain cooling during NREM sleep. Their EEG profiles during NREM sleep resemble the EEG profiles of subjects who have been sleep deprived. Further studies of NREM sleep homeostasis in patients with SAD seem warranted.
Schwartz
P J
PJ
Department of Psychiatry, VAMC, Dayton, Ohio 45428, USA.
Rosenthal
N E
NE
Wehr
T A
TA
D000328:Adult; D000513:Alpha Rhythm; D001833:Body Temperature Regulation / Q000502:physiology*; D001921:Brain / Q000503:physiopathology*; D003700:Delta Rhythm; D004569:Electroencephalography; D005260:Female; D006706:Homeostasis / Q000502:physiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D012016:Reference Values; D016574:Seasonal Affective Disorder / Q000175:diagnosis / Q000503:physiopathology* / Q000523:psychology; D012881:Skin Temperature / Q000502:physiology; D012894:Sleep Stages / Q000502:physiology*; D013826:Theta Rhythm