The data on circadian rhythms of melatonin secretion in women of perimenopausal (n=39) and postmenopausal (n=52) age are presented. Each group was divided into control (without sleep disorders) and main group (with sleep disorders). The saliva was collected 4 times a day (6.00-7.00, 12.00-13.00, 18.00-19.00, 23.00-24.00). The study revealed an association between sleep disorders and decreased level of melatonin only in women of perimenopausal age.