Context: Little is known about the association of low endogenous testosterone levels and abnormal sleep patterns in older men, although pharmacological doses of testosterone are associated with increased severity of sleep apnea and other sleep disturbances.
Objective: The objective of the study was to examine the association between serum testosterone levels with objectively measured sleep characteristics.
Design: This was a cohort study.
Setting: Community-dwelling men aged 65 yr or older from six clinical centers in the United States participated in the study.
Participants and main outcome measures: A total of 1312 men had baseline total testosterone levels measured in 2000-2002, followed 3.4 yr later by 72-h (minimum) actigraphy and one-night in-home polysomnography to assess sleep duration, sleep fragmentation, and sleep apnea. Analyses were performed by quartile of total testosterone and categorically defined low vs. higher total testosterone (<250 ng/dl vs. > or =250 ng/dl). Lifestyle and body size were covariates.
Results: Total testosterone levels were unrelated to age or duration of sleep. Men with lower testosterone levels had lower sleep efficiency, with increased nocturnal awakenings and less time in slow-wave sleep as well as a higher apnea-hypopnea index and more sleep time with O(2) saturation levels below 90%. Low testosterone levels were associated with overweight, and all significant associations were attenuated or absent after adjusting for body mass index or waist circumference. In a post hoc analysis in men with higher body mass index (>27 kg/m2), testosterone was significantly associated with more periods awake after sleep onset and lower sleep efficiency.
Conclusion: Low total testosterone levels are associated with less healthy sleep in older men. This association is largely explained by adiposity. Clinical trials are necessary to determine whether body weight acts directly or indirectly (via low testosterone) in the causal pathway for sleep-disordered breathing in older men.