Low total testosterone not linked to worse sleep quality or duration for older men
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Key takeaways:
- Older men with worse sleep quality and irregular sleep duration have a higher frailty index score.
- Mean total testosterone level is not linked to sleep quality or sleep duration.
Testosterone level does not influence sleep quality or sleep duration among older men, according to findings published in BMC Geriatrics.
“There are a number of possible mechanisms linking sleep and frailty,” Seema D. Sharma, MBBS, MRes, MRCP, clinical research fellow in the division of musculoskeletal and dermatological sciences, faculty of biology, medicine and health at University of Manchester in the U.K., and colleagues wrote. “Sleep disorders may be a marker of conditions including poor health and comorbidities which, by themselves, impair sleep and increase the likelihood of frailty or death. Other possible mechanisms including hormonal factors have been suggested. We were interested in this analysis at the potential influence of testosterone on the relationship between sleep and frailty.”
Sharma and colleagues collected data from men aged 40 to 79 years who participated in the European Male Aging Study. Men attended a baseline visit where they completed questionnaires and functional performance measures, and had a fasting blood sample collected. Participants attended a follow-up at a mean 4.3 years, where additional questionnaire data, including information on sleep quality and sleep duration, were collected. Frailty index was calculated using 39 health deficits, including self-reported comorbidities, selected questionnaire items, impaired physical function and low cognition. Sleep quality was assessed using a questionnaire adapted from the Air Traffic Controller Health Change Study. Scores ranged from 0 to 20, with a higher score indicating worse sleep quality. Short sleep duration was categorized as less than 6 hours per night and long sleep duration was defined as 9 hours of sleep or more per night. Low testosterone was defined as a concentration below 10.5 nmol/L.
The study included data from 2,393 men (mean age, 63.3 years). Of the study group, 17.1% were considered pre-frail with a frailty index of 0.2 to 0.35, 7.1% were defined as frail with a frailty index of more than 0.35, and 75.8% were considered robust with a frailty index of 0.2 or less. Mean sleep duration was 7.01 hours, with 57.3% of men having a good sleep quality score of 0 to 4 and 4.2% having a poor sleep quality score of 15 to 20.
Testosterone level was not associated with sleep duration.
Higher frailty index was associated with worse sleep quality among the study group. Men with a sleep quality score of 15 to 20 had a worse frailty index than those with a sleep quality score of 0 to 4 (relative frailty index = 1.57; 95% CI, 1.38-1.78). Men who slept less than 6 hours per night (relative frailty index = 1.16; 95% CI, 1.06-1.28) and those who slept 9 hours or more (relative frailty index = 1.11; 95% CI, 1-1.23) had a higher frailty index than men who slept 6 to 9 hours per night.
In multinomial regression analysis, men with a sleep quality score of 15 to 20 were more likely to be frail (RR = 9.88; 95% CI, 4.22-23.14) or pre-frail (RR = 3.34; 95% CI, 1.69-6.62) than men with a sleep quality score of 0 to 4.
“Our data showed that adjustment for testosterone did not influence the observed strength of association between sleep parameters and frailty,” the researchers wrote. “This suggests that testosterone is unlikely to be a major contributor to potential causal mechanisms linking the relationship between sleep and frailty.”
Perspective
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The relationship between sleep quality and frailty is poorly understood, and this is due, in part, to the different study designs and potential biological mechanisms that have been suggested in the development of this relationship.
Low testosterone is suggested as a potential biological mechanism, especially among older men. Yet, there is a research gap in the investigation of the interplay between sleep duration and quality, testosterone levels (low vs. high) and frailty. This study by Sharma and colleagues is moving the field by providing a clearer description between the association of impaired sleep quality and duration with frailty after considering the role of testosterone. Of interest is that this association was not explained by the different levels of testosterone. The study provides insight, so future studies can consider other potential biological mechanisms, such as inflammation, that could play a major role in this association.
This cross-sectional study suffers from a common problem that we see in these study designs where directionality can’t be determined. This is important because a body of research has suggested several bidirectional relationships between sleep deprivation and low testosterone, low testosterone and obesity and obesity and sleep deprivation. Therefore, we don’t know if low testosterone or obesity leads to the impairment of sleep duration and quality, or vice versa.
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