We all have heard that we might do without water or air, but if sleep deprived, we won’t be able to survive. That’s how important sleep is to anyone. As a matter of fact, the main cause of the cognitive decline associated with Alzheimer’s is the buildup of amyloid plaques in the brain as we age. Beta-amyloid is a toxic protein that is discharged as a waste product into the fluid surrounding brain cells. If it is not cleared away in a timely manner, it clumps together to form plaques which prevent the brain cells from communicating with one another. The body has mechanism for clearing away this waste product, but the process can be slowed down and thus overtaken, or the rate at which the beta-amyloid is released may exceed the brain capacity to clear it away. Our body gets rid of toxic proteins and other waste products while it is asleep.
Scientists have recently discovered that it is during sleep that this waste disposal system goes into high gear. When we are awake, the brain’s resources are channeled into supporting the activities of waking life, but when we are asleep, these resources become available for “housekeeping” duties, that is, cleaning up the messes of the day and clearing out the toxins that are produced by waking activities. This housekeeping function in the brain is extremely important—that is why we spend approximately one-third of our lives sleeping. Lack of sleep or insufficient sleep robs the brain of the opportunity to carry out the necessary tasks of maintenance and repair.
A research team at the National Institutes of Health conducted a study, published in April 2018, to investigate the connection between sleep and dementia. The team scanned the brains of 20 healthy individuals, aged 22 to 72, after a full night’s sleep and again after a night of sleep deprivation (that is, after 31 hours without sleep). The scans showed that there was an average 5 percent increase in beta-amyloid in the brains of the participants following the night of sleep deprivation. The researchers noted that this increase was located especially in those brain regions (the thalamus and the hippocampus) that are associated with brain functions that decline in the early stages of Alzheimer’s. The team also found that those in the study who had larger beta-amyloid increases reported being in a worse mood after the sleep deprivation than those with lower increases. Earlier studies have shown that the brain regions affected by sleep deprivation are also key areas of the brain involved in mood disorders.Earlier studies, published in 2016, found that elderly individuals who do not get sufficient or proper sleep at night are at a higher risk of developing Alzheimer’s and other dementias. One large study, conducted by the Departments of Medicine at various universities across the U.S. focused on 7,444 women aged 65-80 years. The study found that those women in the study who got 6 hours or less of sleep per night were at a higher risk of developing mild cognitive impairment and/or dementia. The researchers found that elderly individuals suffering from insomnia are at a significantly higher risk of developing dementia than those without a sleeping disorder. Other studies have investigated the connection between sleep apnea and dementia. Sleep apnea, a sleep disorder in which the airway is partially or completely closed for brief periods of time during sleep, disproportionately affects the elderly. The temporary stoppage of breathing caused by sleep apnea disturbs sleep, thus increasing the risk of developing dementia.
Even if elderly people are not afflicted with a sleeping disorder, they tend to sleep less, on average, than younger people. Therefore, it is especially important for the elderly to make an extra effort to get between 7 and 8 hours of uninterrupted sleep each night on a regular basis.