Isoflavones decrease insomnia in postmenopause.

OBJECTIVE: Most postmenopausal women have insomnia. Some of these women also have respiratory sleep disorders. Recent reports have documented that the phytohormones, isoflavones, are capable of reducing the symptoms of climacterium. The purpose of this investigation was to examine subjective and objective sleep parameters and to measure changes in these parameters during treatment with isoflavones in a controlled, double-blinded study in postmenopausal women with insomnia.

METHODS: Two groups of postmenopausal women with insomnia participated in the study: the first received 80 mg isoflavones daily for 4 months, and the second received a placebo for the same period. Sleep analysis consisted of questionnaires and polysomnography. Student's t test and analysis of variance were applied for comparisons between groups, and correlations were tested with Pearson's correlation coefficient.

RESULTS: Thirty-eight women were enrolled in the study. Polysomnography revealed a significant increase in sleep efficiency in the isoflavone group (from 77.9% to 83.9%) when compared with the placebo group (from 77.6% to 81.2%). Isoflavones induced a decrease in the intensity and number of hot flashes and the frequency of insomnia: among the women in the placebo group, 94.7% had moderate or intense insomnia at the beginning of the study, compared with 63.2% at the end, whereas in the isoflavone group, these percentages were 89.5% and 36.9%, respectively.

CONCLUSIONS: In postmenopausal women with insomnia, isoflavone treatment was effective in reducing insomnia symptoms, which was confirmed by increased sleep efficiency as observed by polysomnographic analysis.