Deep sleep may be critical for your heart — but it may also help clear the brain of toxins that play a role in Alzheimher’s disease. Sleep is essential for both cognition and maintenance of healthy brain function, and slow waves in neural activity contribute to memory consolidation, a study published Thursday in the peer-reviewed journal Science concluded. Cerebrospinal fluid during non–rapid eye movement sleep also clears metabolic waste products from the brain.

An increasingly large body of evidence demonstrates that sleep disturbance increases the risk of Alzheimer’s disease, a 2018 review of research in the medical journal JAMA concluded. One such study concluded that individuals with sleep problems had a 1.68 times higher risk for developing cognitive impairment or Alzheimer’s disease and that 15% of Alzheimer’s disease cases may be directly attributable to sleep dysfunction.

Staying mentally and physically active also appears to play a role in preventing cognitive impairment. People age 66 and older who got a hearing aid shortly after being diagnosed with hearing loss were less likely to receive a first-time diagnosis of dementia or depression, or be injured by a fall, in the following three years, a study published recently by the Journal of the American Geriatrics Society and carried out by researchers from the University of Michigan found.

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A bad night’s sleep can also result in a spike in blood pressure that night and the following day, according to recent research. The study, published in a recent edition of the peer-reviewed scientific journal Psychosomatic Medicine and led by scientists at the University of Arizona, offers one possible explanation for why sleep problems have been shown to increase the risk of heart attack, stroke and even death from cardiovascular disease.

Those participants who had lower “sleep efficiency” showed an increase in blood pressure during that restless night. They also had higher systolic blood pressure — the number in a person’s blood pressure reading — the next day. The researchers said getting a good night’s sleep is important for good long-term health, but so is getting quality sleep, and recommended keeping your smartphone in another room, and pulling down the shades if your bedroom faces east.

“Patients with sleep apnea often have compromised heart health,” according to the National Sleep Foundation. “This is because without long, deep periods of rest, certain chemicals are activated that keep the body from achieving extended periods in which heart rate and blood pressure are lowered.” This 2008 study in the Journal of Clinical Sleep Medicine concluded that individuals with severe sleep apnea are at increased risk for coronary artery disease, congestive heart failure, and stroke.