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As you get older you sleep worse. However, the reasons for this remain unknown.
Now a study published in
«Science» have identified how brain circuits involved in regulating sleep and wakefulness degrade over time in mice, which they say paves the way for the design of better drugs for sleep disorders in humans.
“More than half of people over 65 years of age complain about their quality of sleep,” the professor at the
Stanford UniversityLuis de Lecea, co-author of the study.
Research has shown that lack of sleep is linked to an increased risk of multiple health problems, from high blood pressure to stroke heart disease, diabetes, depression, and Alzheimer’s-related brain plaque buildup.
Insomnia is often treated with a class of medications known as hypnoticsbut these do not work very well in the elderly population.
In the new study, the researchers decided to investigate hypocretins, key brain chemicals that are generated only by a small group of neurons in the brain’s hypothalamus, a region located between the eyes and ears.
Of the billions of neurons in the brain, only about 50,000 produce hypocretins.
In 1998, de Lecea and other scientists discovered that hypocretins transmit signals that play a vital role in stabilizing wakefulness.
Since many species experience fragmented sleep as they age, it is hypothesized that the same mechanisms are at play in mammals, and previous research had shown that degradation of hypocretins leads to narcolepsy in humans, dogs, and mice. .
The team selected young (3 to 5 months) and old (18 to 22 months) mice and used fiber-borne light to stimulate specific neurons. They recorded the results using imaging techniques.
What they found was that the older mice had lost approximately 38 percent of the hypocretins compared to younger mice.
They also found that the remaining hypocretins in the older mice were more excitable and more easily activated, making the animals more likely to wake up.
This could be due to the deterioration over time of “potassium channels,” which are biological on-off switches critical to the functions of many cell types.
“Neurons tend to be more active and fire more, and if they fire more, you wake up more often,” says de Lecea.
Identify the specific pathway responsible for sleep loss could lead to better drugs, they argued
Laura Jacobson and Daniel Hoyer of the Florey Institute of Neuroscience and Mental Health in Australiain a comment accompanying the study.
Current treatments, such as hypnotics, “can induce cognitive problems and dependence», and drugs that target the specific channel they could work better.
Although they will need to be tested in clinical trials, an existing drug known as retigabinacurrently used to treat epilepsy and targeting a similar pathway, could hold promise.