Sleep and Aging

We need about eight hours of sleep at night to function well, but for many older folks (e.g., ages 60 and up), sleep becomes a lot harder. Older adults often find it a struggle to even get to sleep and tend to wake up earlier than they used to. The elderly also tend to get up more often in the middle of the night. Granted there may be certain obvious explanations: less bladder control can drive an older person to the bathroom more often and ailments associated with aging can just make it uncomfortable to sleep. But it also appears that your brain chemistry changes with aging. For example, levels of glucocorticoid receptors in the brain are reduced, as are levels of the sleep-associated hormones, melatonin and Growth Hormone Releasing Hormone (GHRH).

The stage of sleep that changes most dramatically with aging is known as "deep non-rapid eye movement sleep" or "NREM sleep." During NREM sleep, you're typically not dreaming, but are deeply relaxed. Older adults show shorter NREM sleep stages, with men more likely to be affected than women. And in very elderly people (90-years old or more), this stage of sleep can even disappear. To compound matters, researchers at the University of Arizona have found that NREM sleep may be important to reinforce certain types of memories.

While the biochemistry of sleep and aging is still poorly understood, research is revealing possible treatment options. In 2001, investigators at the Max Planck Institute of Psychiatry in Germany explored the effects of a type of molecule that binds to receptors in the brain called GABA_A receptors. These receptors are also present at decreased levels in older adults. Under the conditions of the study, the investigators were able to affect NREM sleep without effecting REM sleep, and were able to increase overall sleep quality.

It should be pointed out that not all sleep disturbances are a normal part of aging. Heart disease, depression, and Alzheimers are only some of the conditions that can also be associated with altered sleep patterns. Further, not all sleep disturbances have a biological basis. Alcohol, daytime sleeping, and stress can also contribute to difficulties in sleeping.

The bottom line is that if you have regular insomnia, you should seek the advice of your health care provider.

Sources:

Lancel, M., Wetter, T.C., Steiger, A., Mathias, S. Effect of the GABA_A agonist gaboxadol on nocturnal sleep and hormone secretion in healthy elderly subjects. Am J Physiol Endocrinol Metab 2001 Jul;281(1):E130-7

Van Cauter, E, and Copinschi G. Interrelationships between growth hormone and sleep. Growth Hormone IGF Res 2000, Suppl B: S57-S62, 2000.

Payne, J.D. and Nadel, L. Sleep, dreams and memory consolidation: The role of the stress hormone cortisol.671-678.