Karl Doghramji, MD: Insomnia, and poor sleep in general, seems to be related to a number of consequences that are still being worked on and defined both in older and younger individuals. From a neurocognitive standpoint, we know that poor sleep is related to memory decline, especially working memory and episodic memory, and memory about one’s own recent life. Older individuals, as you know, are afflicted by memory problems, and poor sleep seems to augment that memory decrement.
Secondly, motor abnormalities. So let’s look at falls. Interestingly, many studies have shown that in older individuals, 1 of the strongest predictors of falls, which we worry about a great deal, is poor sleep and short sleep time, independently of hypnotic medications or sleep medications. The impairment in motor behavior in older people could be related to the way they’ve slept the night before.
In the context of the hospital setting, poor sleep is also associated with the risk of delirium. And some studies have shown that by treating poor sleep after admission to a hospital, we can actually diminish the risk of delirium after admission to a hospital. From a systemic standpoint, we know that individuals who sleep more poorly over the course of time have a higher likelihood of developing hypertension and metabolic abnormalities or becoming glucose intolerant, which is very interesting, and that really suggests that insomnia may have significant systemic effects as well as neurocognitive effects.
Going back to the cognitive aspects for a moment, the consequence of cognitive decrements in insomniacs may be along the lines of motor vehicle accidents, which seem to be higher in rates with older individuals. As I mentioned before, falls as well. Insomnia seems to contribute to mood decline. Over the course of many years, insomniacs have a higher risk of developing major depression. And interestingly, people who have had treatment of depression, successful treatment after achieving remission, have a higher rate of having another depressive episode if insomnia persists.
We know that pain disorders are quite comorbid with insomnia. Interestingly, sleeping more poorly, or sleeping less, seems to increase pain sensitivity. So listless sleep seems to augment pain complaints. Interestingly, the opposite is true as well. Helping people sleep better seems to decrease their sensitivity to pain and diminish their pain-related complaints.
Data with older individuals have shown across the course of 20 years that those who sleep more poorly or sleep less have a lower survival rate, a higher mortality rate, than individuals who sleep more, which is very interesting. Of course, it’s not clear that there is a cause-and-effect relationship here. But it suggests to us that sleep may have some rejuvenation or restorative function, which is important in terms of longevity in human beings.