European researchers looked at 147 adults between the ages of 20 and 84. With two MRI scans, they examined the link between sleep problems like insomnia and the study participants' brain volume. The first scan was taken before patients completed a questionnaire pertaining to their sleep habits. The second scan was done approximately 3½ years later.
The questionnaire showed that 35% of those in the study met the criteria for poor sleep health. Investigators found that those with sleep problems had a more rapid decline in brain volume or size over the course of the study than those who slept well.
The results were even more significant in participants over the age of 60.
Numerous studies have showed the importance of sleep and the effect sleep deprivation can have on our brains. It is well-known that poor sleep patterns can contribute to such brain disorders as Alzheimer's and dementia.
So it stands to reason that, if a lack of sleep can lead to memory loss, the size of the brain would also be affected.
"We know that a lack of sleep can lead to all kinds of problems," explained Dr. Neal Maru, a neurologist and sleep specialist with Integrated Sleep Services in Alexandria, Virginia, who is not associated with the study. "Poor sleep can affect our immune systems, our cardiovascular health, weight and, of course, memories. But we still don't know why.
"Studies have shown poor sleep can cause protein buildup in the brain that attacks brain cells. So we're still trying to put the puzzle together."
The study authors agree.
"It is not yet known whether poor sleep quality is a cause or consequence of changes in brain structure," said author Claire Sexton of the University of Oxford in the United Kingdom.
"There are effective treatments for sleep problems, so future research needs to test whether improving people's quality of sleep could slow the rate of brain volume loss. If that is the case, improving people's sleep habits could be an important way to improve brain health."
"The problem is, we really don't know what comes first," Maru agreed. "Is it a sleep problem that causes the atrophy (wasting away of a body part), or is it the atrophy that causes the sleep problems? That's a question we need to sort out."