The groggy, foggy, irritable state we operate in after a poor night’s sleep is usually sufficient to encourage us to catch up on rest as soon as possible.
If that weren’t enough, though, there’s emerging evidence that poor sleep over long periods of time may be detrimental to several aspects of overall health. Sleep deficits can lead (pdf) to problems with cardiovascular and immune system health, and as researchers discussed at the Milken Institute’s Future of Health Summit on Tuesday (Oct. 29), it may play a role in developing dementia later in life, too.
“Sleep disorders and insufficient sleep contribute to Alzheimer’s decades before people develop the disorder,” Ruth Benca, a psychiatrist at the University of California, Irvine, said during a panel on brain health at the summit in Washington, DC.
Benca’s work has tracked the relationship between sleep—particularly the deep sleep known as rapid-eye movement (REM)—and its relationship to developing dementia later in life. In 2017, she and her team published work following healthy individuals with a variant of a gene called APOE that puts them at a higher risk of developing Alzheimer’s. They found that individuals who reported lower-quality sleep tended to have larger buildups of the proteins associated with Alzheimer’s disease, called amyloid and tau, in the fluid surrounding their brains than those who reported sleeping well. It seemed, they thought, that the process of sleep might be clearing some of these buildups.
Subsequent work has backed up that theory. The same year, another study found that among a cohort of adults over 60, those who took longer to enter REM sleep and dreamt less were at an elevated risk of developing dementia. Last year, researchers from the National Institutes of Health in Bethesda, Maryland published the results of a study that found healthy participants who agreed to be woken up hourly for a night (yeesh) had higher levels of amyloid the following day. And earlier this year, a separate group from Washington University School of Medicine found that older adults who got less REM sleep were likely to have higher amounts of tau, too.
The reverse relationship could be true: Buildups of amyloid and tau could contribute to lack of sleep. Research has also shown that people with Alzheimer’s have disrupted sleep cycles.
That said, if sleep does play a causal role in dementia, it may be a future target for new therapies or preventative interventions for the disease.
Ideally, most of us should be getting about seven hours of sleep per night—although some people need more, Benca said. Getting enough sleep should be considered a lifestyle modification for cognitive and physical health, much like exercising, and abstaining from smoking and excessive drinking.
Of course, it’s hard to get a decent night’s sleep every day. Benca advised that we should think about sleep the same way we think about getting a nutritious diet: There are going to be days when it’s impossible to maintain. Just try to make sure that most nights of the week you’re getting enough shut eye, and catch up on rest when you can.