Tung Wai Auyeung1, Timothy Kwok2, Jason Leung3, Jenny Shun Wah Lee2, Claes Ohlsson4, Liesbeth Vandenput4, Yun Kwok Wing5, Jean Woo2. 1. Department of Medicine and Geriatrics, Pok Oi Hospital and Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China. Electronic address: auyeungtw@gmail.com. 2. Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Hong Kong, China. 3. School of Public Health, The Chinese University of Hong Kong, Hong Kong, The Jockey Club Centre for Osteoporosis Care, The Chinese University of Hong Kong, Hong Kong, China. 4. Centre for Bone and Arthritis Research, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 5. Department of Psychiatry, The Chinese University of Hong Kong, Hong Kong, China.
Abstract
BACKGROUND: Testosterone level follows a circadian rhythm. However, whether sleep duration and disturbances can affect testosterone level, muscle mass, and strength remains unknown. OBJECTIVE: To examine the relationship of sleep duration and disturbances to testosterone level, muscle mass, muscle strength, and walking speed. PARTICIPANTS AND METHODS: We recruited 1274 community-dwelling men older than 65 years of age. Their early morning testosterone level was assayed by mass spectrometry. A sleep questionnaire was administered to enquire about their reported sleep duration, prolonged sleep latency (>0.5 hour), and subjective insomnia complaint. Muscle mass was measured by dual-energy x-ray absorptiometry. Testosterone level, muscle mass, handgrip strength, and walking speed were tested against sleep duration and disturbances. RESULTS: Testosterone increased with increasing sleep duration up to 9.9 hours, after which it decreased, giving rise to an inverted U-shaped relationship (P for quadratic trend <.05). A similar inverted U-shaped relationship occurred between sleep duration and muscle mass and function. Earlier go-to-bed time, despite being associated with a higher testosterone level (P < .05), was associated with weaker grip strength (P < .05). Earlier wake-up time was associated with higher muscle mass (P < .05) but neither grip strength nor walking speed. Neither prolonged sleep latency nor insomnia was associated with testosterone levels. However, prolonged sleep latency was associated with lower muscle mass (P < .05), weaker grip strength (P < .05), and slower walking speed (P < .001). Insomnia, on the other hand was associated with weaker grip strength (P < .05) and slower walking speed (P < .001) but not muscle mass. CONCLUSIONS: Sleep duration and disturbances can affect testosterone level, muscle mass, and its function. Whether optimization of sleep can ameliorate age-associated decline in sex hormone and muscle performance warrants further studies.
BACKGROUND:Testosterone level follows a circadian rhythm. However, whether sleep duration and disturbances can affect testosterone level, muscle mass, and strength remains unknown. OBJECTIVE: To examine the relationship of sleep duration and disturbances to testosterone level, muscle mass, muscle strength, and walking speed. PARTICIPANTS AND METHODS: We recruited 1274 community-dwelling men older than 65 years of age. Their early morning testosterone level was assayed by mass spectrometry. A sleep questionnaire was administered to enquire about their reported sleep duration, prolonged sleep latency (>0.5 hour), and subjective insomnia complaint. Muscle mass was measured by dual-energy x-ray absorptiometry. Testosterone level, muscle mass, handgrip strength, and walking speed were tested against sleep duration and disturbances. RESULTS:Testosterone increased with increasing sleep duration up to 9.9 hours, after which it decreased, giving rise to an inverted U-shaped relationship (P for quadratic trend <.05). A similar inverted U-shaped relationship occurred between sleep duration and muscle mass and function. Earlier go-to-bed time, despite being associated with a higher testosterone level (P < .05), was associated with weaker grip strength (P < .05). Earlier wake-up time was associated with higher muscle mass (P < .05) but neither grip strength nor walking speed. Neither prolonged sleep latency nor insomnia was associated with testosterone levels. However, prolonged sleep latency was associated with lower muscle mass (P < .05), weaker grip strength (P < .05), and slower walking speed (P < .001). Insomnia, on the other hand was associated with weaker grip strength (P < .05) and slower walking speed (P < .001) but not muscle mass. CONCLUSIONS: Sleep duration and disturbances can affect testosterone level, muscle mass, and its function. Whether optimization of sleep can ameliorate age-associated decline in sex hormone and muscle performance warrants further studies.