Aging often rhymes with bad sleep

(Washington) It’s well known that getting a good night’s sleep gets more complicated with age. But the biological reasons remain poorly understood.

This is why a team of American researchers studied how the brain circuits involved in sleep and wakefulness deteriorate over time in mice. Their work could thus make it possible to develop better treatments to remedy this problem in humans.

“More than half of people over the age of 65 complain about the quality of their sleep,” Stanford University professor Luis de Lecea, co-author of this study published Thursday in the journal, told AFP. Science.

Lack of sleep is associated with increased risks of hypertension, cardiac arrest, diabetes, or even depression. Insomnia is treated by taking sleeping pills, but these are not always effective.

For their work, Luis de Lecea and his colleagues decided to focus on hypocretins, neurotransmitters that are only generated by a small fraction of neurons in the brain — about 50,000 out of several billion.

In 1998, the professor and other scientists discovered that hypocretins transmit signals that play a vital role in stabilizing wakefulness.

Studies have shown that the breakdown of hypocretins can lead to narcolepsy (excessive sleep time and involuntary drowsiness) in humans, dogs and mice.

The researchers selected young (three to five months) and old (18 to 22 months) mice and used light to stimulate specific neurons.

Conclusion: the older mice had lost about 38% of hypocretins compared to the young ones.

And the remaining ones were triggered more easily.

“Neurons tend to be more active and fire up more, and if that’s the case, you wake up more frequently,” Luis de Lecea explained.

Identifying the mechanisms responsible for sleep loss could aid in the development of better drugs, two researchers from the Florey Institute of Neuroscience and Mental Health in Australia pointed out, in a separate commentary article also published in Science.

Existing treatments “can lead to cognitive difficulties or falls,” and drugs aimed at more specific targets might work better, they say.

Clinical trials will be necessary, but the antiepileptic retigabine could in this context prove promising, according to Luis de Lecea.