Effects of REM sleep and ambient temperature on hot flash-induced sleep disturbance.
OBJECTIVE
To determine whether hot flashes produce sleep disturbance in postmenopausal women.


METHODS
This study was performed in a university medical center laboratory with 18 postmenopausal women with hot flashes, six with no hot flashes, and 12 cycling women, all healthy and medication free. Polysomnography, skin and rectal temperatures, and skin conductance to detect hot flashes were recorded for four nights. Nights 2, 3, and 4 were run at 30 degrees C, 23 degrees C, and 18 degrees C in randomized order.


RESULTS
During the first half of the night, the women with hot flashes had significantly more arousals and awakenings than the other two groups and the 18 degrees C ambient temperature significantly reduced the number of hot flashes, from 2.2 +/- 0.4 to 1.5 +/- 0.4. These effects did not occur in the second half of the night. In the first half of the night, most hot flashes preceded arousals and awakenings. In the second half, this pattern was reversed.


CONCLUSIONS
In the second half of the night, rapid eye movement sleep suppresses hot flashes and associated arousals and awakenings. This may explain previous discrepancies between self-reported and laboratory-reported data in postmenopausal women with hot flashes.
Freedman
Robert R
RR
Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, MI 48201, USA. aa2613@wayne.edu
Roehrs
Timothy A
TA
D003080:Cold Temperature; D004569:Electroencephalography; D005260:Female; D019584:Hot Flashes / Q000150:complications*; D006358:Hot Temperature; D006801:Humans; D008875:Middle Aged; D017698:Postmenopause; D012720:Severity of Illness Index; D012881:Skin Temperature; D012892:Sleep Deprivation / Q000209:etiology* / Q000503:physiopathology; D012895:Sleep, REM