How Old Age Influences Circadian Rhythms

Scientists at the University of California in Los Angeles (UCLA) recently finished conducting a new study, which demonstrates that old age has a significant influence on the master circadian clock in the human brain.

This region is called the suprachiasmatic nucleus (SCN). The team determined that critically-important patterns of neural activity that can usually be picked up in this area of the brain start to decline, and lose their focus, as people reach middle age.

Studies such as this one could have significant implications on seniors who currently have a hard time adapting to time changes, or who cannot get enough rest. The new work was led by UCLA Chancellor Gene Block.

In addition to controlling the timing of the sleep–wake cycle inside the human body, the SCN is also involved in a variety of other rhythmic and non-rhythmic processes. As such, understanding how it functions could lead to improvements in a large number of fields of research.

The structure is located inside the hypothalamus of humans and many other mammalian species. The circadian rhythm is responsible for the way the body changes in response to day and night.

“Aging has a profound effect on circadian timing,” explains Block, who also holds an appointment as a professor of psychiatry and biobehavioral sciences, and of physiological science, at the university.

“It is very clear that animals' circadian systems begin to deteriorate as they age, and humans have enormous problems with the quality of their sleep as they age, difficulty adjusting to time-zone changes and difficulty performing shift-work, as well as less alertness when awake,” he adds.

“There is a real change in the sleep–wake cycle. The question is, what changes in the nervous system underlie all of that? This paper suggests a primary cause of at least some of these changes is a reduction in the amplitude of the rhythmic signals from the SCN,” the expert goes on to say.

Interestingly, investigations conducted on the SCN of lab mice revealed no significant alterations to the molecular mechanisms that generate these critical neural activity rhythms. The latter were disrupted in middle age, but not because the mechanisms themselves were failing.

This means that their function could easily be augmented, as soon as investigators figure out how to do that. Boosting these molecular mechanisms could prevent the deterioration of SCN neural activity patterns, eliminating the undesired health effects.

Until now, experts didn't even know that the central circadian clock was responsible for triggering the decline. With the new data, it may be possible for other researchers to carry the work even further.

Funds for the research were provided by the US National Institutes of Health (NIH) and the UCLA.