SLEEP SPINDLE FREQUENCY CHANGES DURING THE MENSTRUAL-CYCLE

Five healthy adult women aged 20 to 28 had 12-15 polysomnographic reco rdings, as well as daily basal body temperature and multiple LH, FSH, estrogen and progesterone measurements taken during a single menstrual cycle. Sleep stages were scored both visually and with a spindle and delta-wave, real-time, automatic analysing system. A cubic growth-curv e model showed that the frequency of sleep spindles changed markedly o ver the menstrual cycle: spindle frequency was lowest about 18 days be fore onset of menses and highest 3 days before onset of menses. Slow w aves did not change. The percentages of Stage 1 and REM sleep showed s mall changes during the menstrual cycle, and other parameters of visua lly scored sleep showed no tendency to change. Spindle frequency may r eflect the effects of sex hormones on the reticular thalamic nucleus a nd may be a quantitative marker of premenstrual sleep disturbances.