The aim of this study was to evaluate the relationship between various characteristics of objectively recorded hot flashes and sleep disturbances in breast cancer patients.
Fifty-six women who had completed a similar treatment protocol for a first diagnosis of breast cancer within the previous 3 months wore ambulatory sternal skin conductance and polysomnography devices for a home-based nighttime recording of hot flashes and sleep.
Hot flash frequency was not associated with polysomnographic variables (r = −0.18 to 0.21) or beta-I and beta-II electroencephalographic activities (r = −0.01 and 0.03) but was significantly correlated with increased slow (r = 0.28) and delta (r = 0.32) electroencephalographic activities. A slower hot flash onset and a longer hot flash duration were associated with greater polysomnographic impairments (r = −0.50 to 0.48). Greater sleep disturbances were found during hot flash onset or hot flash plateau as compared with the pre–hot flash period (greater percentage of wake time, lower percentage of stage II sleep, and lower percentage of rapid eye movement sleep, all P values < 0.05). The probability that a stage change to a lighter sleep occurred was significantly greater during hot flash onset (11%) than during hot flash plateau (6%; P = 0.02).
This study suggests that the speed and duration of hot flashes would contribute more importantly to sleep alterations than hot flash frequency. Sleep disturbances tend to occur simultaneously with hot flashes, suggesting that these two nocturnal symptoms are manifestations of a higher-order mechanism involving the central nervous system.
From the 1School of Psychology, Université Laval, Québec, Quebec, Canada; 2Laval University Cancer Research Center, Quebec, Canada; 3Centre de recherche du CHU de Québec, Quebec, Canada; and 4Centre de recherche Université Laval Robert-Giffard, Quebec, Canada.
Received November 22, 2012; revised and accepted January 17, 2013.
Funding/support: This study was supported by salary support awards from the Canadian Institutes of Health Research (M.H.S. and J.S.) and the Fonds pour la recherche en santé du Québec (M.H.S., J.S., and A.C.G.). This study was also supported in part by a grant from the Canadian Breast Cancer Research Alliance (DEX 017529).
Financial disclosure/conflicts of interest: None reported.
Address correspondence to: Josée Savard, PhD, Laval University Cancer Research Center, 11 Côte du Palais, Québec, Quebec, Canada G1R 2J6. E-mail: firstname.lastname@example.org