Gender difference of slow wave sleep in middle aged and elderly subjects

Abstract

The amount of slow wave sleep (SWS) declines with increasing age 1,2 and it is well known that gender difference on sleep parameters have been noted in the middle aged and elderly. 3,4 The purpose of this study is to investigate gender effects on slow wave activity in middle aged and elderly subjects by spectral analysis. SUBJECTS AND METHODSEight healthy male subjects (61.50 ± 4.66 years) and eight female subjects (62.38 ± 6.65 years) participated in this study. None of the participants had had a significant medical history and during the study were free of medication. The subjects were asked to avoid sleep during the day and sleep electroencephalograms were recorded for three consecutive nights at their homes using an ambulatory monitoring system to maintain their daily sleep conditions. Third-night EEG were visually scored by a 20-s epoch according to the criteria of Rechtschaffen and Kales. The EEG (C3-A2) was digitized at a sampling rate of 125 Hz (the sampling period was 8 ms). Power spectra were calculated by FFT over 1024 data points with a cosine bell window. The spectral power through nocturnal sleep and the mean spectral power per 30 s were obtained for two frequency bands (0.5-2 Hz and 2-4 Hz). For statistical analysis, the spectral power was normalized by a logarithmic transformation and the Mann-Whitney U test was used to compare spectral power between genders. Figure 1 shows two hypnograms for both male and female subjects. The sleep continuity of a male subject aged 61 years was maintained, while a female subject aged 72 years showed long awakenings in the latter part of sleep. The length of SWS was shown to be longer in the female than the male. There were no significant gender differences in visually scored EEG parameters: time in bed, sleep period time, total sleep time, sleep efficiency, number of awakenings, sleep latency, REM latency and percentages of stage W, 1, 2, REM. However, females showed a higher percentage of stage 3 + 4 as compared with males (mean % ± SD, Psychiatry and Clinical Neurosciences (1999) RESULTS AbstractSleep EEG of eight healthy males and eight females aged 54-72 years were recorded at their homes. The electroencephalograms were visually scored and analyzed by spectral analysis using the FFT method. There were no significant differences in sleep parameters except for a higher percentage of stage 3 + 4 in females. The spectral power of the delta band EEG was classified into two frequencies: 0.5-2 Hz and 2-4 Hz. The total amount of the delta band spectral power through the night was significantly larger in females. Periodic fluctuation of delta band power was observed in females along with non-rapid eye movement-rapid eye movement cycles.

Gender Differences in Polysomnographic Sleep in Young Healthy Sleepers

“…Our gender difference data concur with those from middle-aged and elderly populations (Fukuda et al, 1999;Hume et al, 1998; N. Goel, H. Kim, and R. P. Lao 910 et al, 1998;Rediehs et al, 1990;Reynolds et al, 1985;Wauquier et al, 1992;Webb, 1982). However, they contrast with findings from a number of studies that failed to detect gender differences in younger populations using PSG (Armitage, 1995;Armitage et al, 2000;Carrier et al, 2001;Dijk et al, 1989;Ehlers and Kupfer, 1997;Elsenbruch et al, 1999).…”

“…However, objective polysomnographic (PSG) measures in these groups show the opposite pattern; women have better sleep quality than men, including more slow-wave sleep (SWS), more rapid-eye movement (REM) sleep, and fewer night-time awakenings (Fukuda et al, 1999;Hume et al, 1998;Kobayashi et al, 1998;Rediehs et al, 1990;Reynolds et al, 1985;Wauquier et al, 1992;Webb, 1982). Elderly women also show longer REM latencies than elderly men (Hoch et al, 1988;Rediehs et al, 1990).…”

About Sleep's Role in Memory

“…976). Women sleep longer and still have a higher SWS percentage than men, whereas men show increased non-REM sleep stages 1 and 2 (424,587,652,952). In a study in 2,600 participants aged 37 to 92, gender explained 14.6% of the variance in SWS percentage and 10.9% of stage 2 sleep percentage (976).…”

Improving sleep and cognition by hypnotic suggestion in the elderly

“…Only females were recruited to avoid known gender effects on sleep architecture and suggestibility (Carrier et al, 2001;Fukuda et al, 1999;Page and Green, 2007). One subject was excluded due to lacking sleep, two others did not keep caffeine restriction in one of the two experimental sessions.…”