As men reach middle-age, they tend to lose their hair, their testosterone levels have already begun to decline, and they experience less deep sleep. A researcher from the University of Montreal believes there is a definite link between the latter two events, and he say his study is the first to uncover a relationship between declining testosterone and less deep sleep.
Experts typically recognize five stages of sleep, with stage 1 being drowsiness, stage 2 as a period of light sleep, stages 3 and 4 as deep sleep, and then stage 5, REM (rapid eye movement) sleep. The two deep sleep stages are known as slow-wave or delta sleep, with stage 4 representing a deeper stage of sleep. Both of these stages shorten dramatically in older people, so they tend to get less total deep sleep than younger individuals do. Older people enter REM sleep faster and stay there longer than younger people.
Deep sleep typically represents 10 to 20 percent of a young man’s total sleep time. Once men are older than 50, stage 3 and stage 4 sleep decreases to 5 to 7 percent, and it can disappear completely after age 60.
Zoran Sekerovic, the author of the study, found a correlation between testosterone levels in men older than 50 and the quality of their deep sleep. This association does not exist in younger men because their neuronal circuits are intact. As men age, however, neurons are lost and synchronization of cerebral activity is not as effective, which results in a loss of deep sleep.
“Deep sleep requires great synchronization,” noted Sekerovic. “Low levels of testosterone intensity the lack of synchronization and can explain 20 percent of men’s inability to experience deep sleep.” Sekerovic believes declining testosterone levels have an effect on sleep, and not the other way around, as other studies have reported.
Testosterone levels begin to decline in men around age 30 at a rate of 1 to 2 percent per year. Correcting deep sleep deprivation may not be as easy as starting testosterone therapy, however. Side effects can include acne, fluid retention, breast enlargement, worsening of sleep apnea, a decrease in testicular size, changes in cholesterol and lipid levels, decline in sperm count, and an increase in PSA (prostate specific antigen), a possible indicator of prostate cancer. Sekerovic notes that “it will be essential to better understand the mechanisms that lead to the loss of deep sleep” before middle-aged men see their doctors about taking testosterone for sleep loss.