It doesn't take a research study to tell older people that it's tougher to get a good nights sleep as we age. This is also true for a variety of mammals. The biology behind that phenomenon has not been well understood, however. New research has provided some insights into the sleepless nights of the aging and elderly. Reporting in Science, investigators have used a mouse model to determine that the brain circuitry that helps control sleep and wakefulness breaks down over time.
Over half of people who are 65 and older have complaints about sleep quality, study co-author and Stanford University professor Luis de Lecea told AFP.
While there are some treatments for insomnia, like hypnotic drugs such as Ambien, they're not very effective for the elderly. Sleep deprivation can lead to a variety of health problems, and has been associated with diseases including diabetes and Alzheimer's.
Previous work by de Lecea and others has indicated that molecules called hypocretins play a role in stabilizing wakefulness. The degradation of hypocretins has also been shown to lead to narcolepsy in mouse and dog models, and humans as well. Hypocretins are made by a relatively small number of neurons (Hcrt neurons) that are clustered in a region of the brain known as the hypothalamus, which is known to be involved in regulating sleep. Other neurons that produce a variety of hormones are also found in the hypothalamus, a central regulator of many crucial functions.
In this study, the researchers used two groups of mice, one in which the ages were between three and five months and another with older mice who were 18 to 22 months old. Using light, the researchers stimulated specific neurons and recorded the signaling. This research revealed that in older mice, there was a loss of hypocretins; the reduction was about 38 percent compared to younger mice. The hypocretins in the older mice were also dysfunctional; they were overly excitable and easily triggered, so the animals were easier to arouse from sleep.
The researchers speculated that potassium channels may be deteriorating, leading to that overexcitability. If the biochemical pathway that's directly involved is identified and confirmed in people, it could lead to the development of better drugs to treat insomnia in oder people.
There is also an existing epilepsy drug called retigabine, "which targets a similar pathway" and "could be promising," said de Lecea.