16 December 2019: 

Summary

The WHI studies (both the clinical and the observational) have provided a wide arrow of information on many aspects of menopause and hormone therapy. A new WHI release, which included a subset of women enrolled in the WHI trials, correlates DNA-derived data with sleep (1). While it is difficult to put into the format of Menopause Live all the details of this study, here are the main features: 1796 European Americans, 1349 Afro Americans, mean age 64. Blood samples from the participants at entry allowed extraction of leucocyte DNA and determining the telomere length (TL). Sleep duration was recorded through a questionnaire, asking women to disclose their normal sleep duration (in round hours) and the degree of sleep disturbance (using the WHI Insomnia Rating Scale). As part of the WHI study protocol, many other demographic, clinical and laboratory variables a ; some were used in the statistical evaluation and adjustments of the current main study data. The bottom-line results can be summarized as follows: mean TL was 214-base-pairs longer in Afro Americans than in European Americans; each 1-year increase in age was associated with 23-base-pair shorter TL, on average; each additional daily hour of sleep beyond 5 hours, approximately, was associated with a 27-base-pair longer TL in the entire sample.

Commentary

A telomere is a nucleoprotein complex found in the extremes of the chromosomes, where its structure is different from the rest of the chromatin since it contains non-coding DNA. The role of the telomeres is to hinder the loss of important DNA from chromosome ends during replication. Short leukocyte TL is associated with increased risks of mortality, cardiovascular disease, diabetes, Alzheimer's disease and probably with cancer as well.

Adequate duration of sleep and sufficient sleep quality are vital for maintaining good health and wellbeing. Any disturbance of normal sleep patterns may lead to serious adverse outcomes, which include cardiovascular and metabolic derangements, cognitive impairment, osteoporosis, and an increase in the incidence of cancer. Interestingly, sleep and TL are independently associated with aging. With the advancement of age, more people complain about sleep problems, and TL is constantly shortening. The current study suggested that women who did not achieve sufficient sleep duration had a TL equivalent to that of women in the US population who were more than 2 years older, on average, than women of the same age who reported sufficient sleep. However, statistically significant associations between sleep disturbance and TL were not recorded. To note, both sleep and TL have a very complex and multifactorial physiological basis. It is, therefore, difficult to establish a direct cause-and-effect association between these two entities. Many previous studies dealt with similar issues and had similar conclusions. Telomere shortening is now recognized as an important sign of cell aging and disease, whereas chronic sleep problems could be related to a higher risk for various diseases. The current WHI data looked at these situations while focusing on a specific segment of the US population - post-menopausal women with different ethnic backgrounds. To summarize, these new data do not add much to the general knowledge on the role of sleep in women’s health, or on the perspectives of the signal of telomere shortening. Improving sleep quality clearly has a beneficial effect on human physiology, whereas finding ways to stop or slow the pace of the changes in TL might prove to carry a significant health advantage.

Amos Pines

Clinical Associate Professor, the Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel; The Hebrew University Hadassah Medical School, Jerusalem, Israel

References

1. Grieshober L, Wactawski-Wende J, Hageman Blair R, Mu L, Liu J, Nie J, Carty CL, Hale L, Kroenke CH, LaCroix AZ, Reiner AP, Ochs-Balcom HM. A cross-sectional analysis of telomere length and sleep in the Women’s Health Initiative. Am J Epidemiol 2019;188:1616-26.
   https://www.ncbi.nlm.nih.gov/pubmed/31145433