What happens when you have a sleepless night

Sleep is important for your heart, your weight, and your overall health, as anyone who has struggled to fall asleep at night knows. Research suggests that poor sleep quality may be linked to Alzheimer’s disease. A new study has shed some light on the relationship.

Early signs of Alzheimer’s include tangles of tau protein in the brain, along with plaques of amyloid-beta. In a study of 119 people aged 60 and older, researchers monitored people’s sleep at home for a week using portable monitors that measured their brain waves as they slept. The volunteers wore a sensor watch to track their body movements throughout the night.

Researchers measured levels of amyloid and tau proteins in the brains and cerebrospinal fluid of the volunteers. They found a link between low levels of slow-wave sleep and high levels of tau protein in the brain. The tau-amyloid ratio was also higher in the cerebrospinal fluid of people with poor sleep quality.

These findings were published in the scientific journalTranslational Medicine.

Not long ago, the same group of researchers discovered that even a single night of poor sleep can increase levels of the protein tau. The researchers collected cerebrospinal fluid samples from eight adults who were monitored during a single night of sleep and then 36 hours of sleep deprivation. They found that tau levels increased by 51.5 percent in the sleep-deprived subjects. In a parallel experiment, they found that sleep-deprived mice had twice the amount of tau as well-rested mice.

David Holtzman, MD, chair of the Department of Neurology at Washington University School of Medicine in St. Louis, and author of both studies, believes the link between poor sleep and Alzheimer's disease is becoming increasingly clear.

These new findings have implications for Los Angeles sleep specialist Michael J. Breus, PhD, who is the author of several books on sleep.

"When you don't get three or four hours of sleep, it slows down the brain's waste removal, leaving amyloid and tau proteins around the brain and brain cells. They basically choke off nerve endings, which is a big contributor to Alzheimer's disease," Breus explains.

"This is the first time we've seen a link between disrupted sleep, poor sleep quality, and tau protein in the brain," said Nick McKeehan, assistant director of the Division of Aging and Alzheimer's at the Alzheimer's Drug Foundation of America. "This is an important piece to the puzzle."

“Poor sleep quality may increase the risk of Alzheimer’s disease, but Alzheimer’s disease can also disrupt sleep. More research is needed to draw firm conclusions,” he added.

Until then, everyone should take a hard look at their sleep habits and find ways to correct mistakes like drinking caffeine late in the day or watching TV before bed. Aim for 7-8 hours of sleep each night. If you’ve made lifestyle changes and still can’t sleep well, consult your doctor.