Sleep duration and sleep‐disordered breathing and the risk of melanoma among US women and men

risk of melanoma among US women and men Melanoma is among the leading causes of cancer incidence and mortality, and death rates are rising. Long and short sleep duration and sleep-disordered breathing (SDB) – snoring and obstructive sleep apnea – have been shown to negatively affect health. In this study, we evaluated the association between sleep duration and SDB and the risk of incident melanoma in three prospective cohorts of US women (Nurses’ Health Study [NHS] and NHS II) and men (Health Professionals Follow-Up Study [HPFS]). The NHS is a study of female registered nurses that started in 1976. The NHS II is a study of younger women that began in 1989. The HPFS is a study of male health professionals that started in 1986. Participants receive questionnaires every two years. Average sleep duration in a 24-hour period, snoring, and physician-diagnosed melanoma were asked multiple times in the studies. Physician-diagnosed obstructive sleep apnea was questioned in the NHS in 2008. Sleep duration and snoring data from the NHS and NHS II were pooled together. HPFS data were analyzed separately, as estrogen may be involved in melanoma pathogenesis. Relative risks (RRs) and 95% confidence intervals of incident melanoma associated with sleep duration and SDB were estimated using Cox proportional hazards models adjusting for age, hair color, number of moles, reaction to the sun, tanning, ultraviolet flux, snoring, and history of night shift work. This study was approved by the Institutional Review Boards of Partners Health Care and the Harvard School of Public Health. During 2,301,445 person-years of follow-up, we documented 880 incident invasive melanoma cases. In the NHS, shift workers were more likely to sleep ≤6 hours per night, and in the NHS and NHS II, there were more snorers in the sleep category of ≥9 hours than any other category. Otherwise, there were no notable trends among different sleep duration categories (Table 1). In the three cohorts, there was no apparent clear relationship between sleep duration and risk of melanoma (Table 2). In the NHS and NHS II, the multivariate RRs for incident melanoma were 0.90 (0.67–1.20) for women sleeping ≤ 6 hours, 1.30 (1.08–1.56) for 8 hours, and 0.76 (0.51–1.12) for ≥ 9 hours (P trend = 0.09). In the HPFS, the multivariate RRs were 1.08 (0.77–1.51) for men sleeping ≤ 6 hours, 0.95 (0.69–1.30) for 8 hours, and 1.06 (0.68–1.67) for ≥ 9 hours (P trend = 0.71). There was no association between melanoma and obstructive sleep apnea in the NHS or snoring in the three cohorts (Tables S1 and S2). Melatonin, an indolamine regulator of circadian rhythms, has anticancer effects and has been found to have antitumor effects in melanoma cell lines. In normal skin, melatonin has antioxidant properties. In melanoma, melatonin can potentiate the oncostatic effects of interleukin-2. Our results suggest that dysregulation of melatonin associated with long and short sleep duration and SDB either have no effect on melanoma risk or have an effect that we were not able to detect, possibly due to a limited number of melanoma cases, particularly among those with ≥ 9 hours of sleep. Our study is limited by the possibility of misclassification of self-reported sleep duration and snoring information. However, previous studies using the same data on sleep duration and snoring found associations with other diseases. In addition, our study population was comprised of Caucasian women, which may limit the generalizability of our findings. In conclusion, in the evaluation of three large cohort studies to prospectively assess the association between sleep duration and SDB and risk of melanoma, we found no relationship between sleep duration and SDB and melanoma risk.