Middle-aged men do not feel as rested in the morning because a reduction in the sex hormone testosterone affects their quality of sleep, according to a new scientific study.
By Richard Alleyne, Science Correspondent of the UK’s Telegraph Online
It has long been thought that a lack of sleep led to a reduction in testosterone but now scientists believe it could be the other way around.
When men reach the age of 30, their testosterone levels drop by one to two per cent every year. By the age of 40, men’s quality of sleep also begins to diminish.
Researchers in Canada have discovered a possible link between decreased testosterone levels and reduced deep sleep.
Zoran Sekerovic, a graduate student from the University of Montreal’s Department of Psychology, has discovered a link between testosterone levels in men over 50 and their quality of sleep, specifically less deep sleep.
He said: “Deep sleep is when the recuperation of body and mind is optimal.”
In young men, “deep sleep” represents 10 to 20 per cent of total sleep. By age 50, it decreases to five to seven per cent. For men over 60, it can disappear altogether.
The University of Montreal researcher said that men in their twenties do not have such a correlation because their neuronal circuits are intact.
Mr Sekerovic said: “With age, there is neuronal loss and the synchronisation of cerebral activity isn’t as good, which is why there is a loss of deep sleep.
“Because deep sleep requires great synchronisation, low levels of testosterone intensify the lack of synchronisation and can explain 20 per cent of men’s inability to experience deep sleep.”
He suggested dwindling testosterone levels are what impact sleep, not vice versa, as other studies have suggested.
He said previous investigations measured daily fluctuations in testosterone levels, which are higher in the morning.
If he is right, his findings could reignite the hormone therapy debate.
Mr Sekerovic said: “The loss of deep sleep is a serious problem that could be treated with testosterone. That would be tremendous progress
“But hormone therapy can have secondary effects. Therefore, it will be essential to better understand the mechanisms leading to the loss of deep sleep.”
The study was conducted under the supervision of Julie Carrier, a professor of psychology at the University of Montreal and director of the Chronobiology Laboratory at the Hôpital du Sacré-Coeur de Montreal.