Disentangling the effects of insomnia and night work on cardiovascular diseases: a study in nursing professionals

Cardiovascular diseases (CVDs) are known to be associated with poor sleep quality in general populations, but they have not been consistently associated with specific work schedules. Studies of CVD generally do not simultaneously consider sleep and work schedules, but that approach could help to disentangle their effects. We investigated the association between insomnia and a self-reported physician diagnosis of CVD in day and night workers, considering all sleep episodes during nocturnal and diurnal sleep. A cross-sectional study was conducted in 1307 female nursing professionals from 3 public hospitals, using baseline data from the “Health and Work in Nursing - a Cohort Study.” Participants were divided into two groups: i) day workers with no previous experience in night shifts (n=281) and whose data on insomnia were related to nocturnal sleep and ii) those who worked exclusively at night (n=340) and had data on both nocturnal and diurnal sleep episodes, as they often sleep at daytime. Multiple logistic regression analysis was performed. Among day workers, insomnia complaints increased the odds of CVD 2.79-fold (95% CI=1.01-6.71) compared with workers who had no complaints. Among night workers, reports of insomnia during both nocturnal and diurnal sleep increased the odds of reported CVD 3.07-fold (95% CI=1.30-7.24). Workers with insomnia had similar probabilities of reporting CVD regardless of their work schedule, suggesting a relationship to insomnia and not to night work per se. The results also highlighted the importance of including evaluation of all sleep episodes (diurnal plus nocturnal sleep) for night workers.

Poor sleep in middle-aged women is not associated with menopause per se

Whether sleep problems of menopausal women are associated with vasomotor symptoms and/or changes in estrogen levels associated with menopause or age-related changes in sleep architecture is unclear. This study aimed to determine if poor sleep in middle-aged women is correlated with menopause. This study recruited women seeking care for the first time at the menopause outpatient department of our hospital. Inclusion criteria were an age ≥40 years, not taking any medications for menopausal symptoms, and no sleeping problems or depression. Patients were assessed with the Pittsburgh Sleep Quality Index (PSQI), modified Kupperman Index (KI), and Menopause Rating Scale (MRS). A PSQI score of <7 indicated no sleep disorder and ≥7 indicated a sleep disorder. Blood specimens were analyzed for follicle-stimulating hormone and estradiol levels. A total of 244 women were included in the study; 103 (42.2%) were identified as having a sleep disorder and 141 as not having one. In addition, 156 (64%) women were postmenopausal and 88 (36%) were not menopausal. Follicle-stimulating hormone and estradiol levels were similar between the groups. Patients with a sleep disorder had a significantly higher total modified KI score and total MRS score (both, P<0.001) compared with those without a sleep disorder. Correlations of the PSQI total score with the KI and MRS were similar in menopausal and non-menopausal women. These results do not support that menopause per se specifically contributes to sleep problems.