Better Sleep Can Prevent Cognitive Decline

By Alex Dimitriu, MD

Sleep is as important to our health as good nutrition and regular exercise. Not getting enough sleep is detrimental to daytime functioning – to our mood, energy, concentration and reaction time – and over the long term, it contributes to obesity and the risk of serious illness. But sleepless nights have implications well beyond making you sleepy the next day. Some of the most exciting research in sleep science is studying the effects of sleep on the brain and what happens when you deprive your brain of restorative sleep. New research suggests that sleeping less than seven to eight hours a night can be linked to memory loss, cognitive decline, and even Alzheimer’s disease.

Our brains don’t sleep when we do.

During waking hours, the brain is bombarded with more stimuli than it can process. When we go to sleep, the brain goes to work, making order out of chaos and archiving memories for later retrieval. It does this by strengthening critical neural connections, discarding unimportant ones, and solidifying new memories.

We’ve all noticed, and research has confirmed, that “sleeping on it” helps us recall a newly learned task. This explains why people suffering memory deficits can recall a name from forty years ago but not what they had for lunch yesterday. Their brains have become less efficient at making new connections and storing new memories. Better sleep may improve this key brain function.

As with every organ in the body that converts fuel into energy, the brain produces waste that accumulates during waking hours and is cleared out while we sleep. There is more space between brain cells while we’re asleep, making it easier for cerebrospinal fluid to flush out toxins. Researchers are just beginning to understand this cleansing process – called the glymphatic system – but it appears that the more waste that’s littering the brain, the easier it is for degenerative diseases to take hold. Among these waste products is beta-amyloid, the toxic protein best known for its presence in the brains of people with Alzheimer’s disease. The glymphatic system, which becomes less efficient as we age, does its work while we sleep, raising the possibility that better sleep can improve the processes that flush beta-amyloid and other toxins from the brain.

Older adults with dementia suffer sleep disturbances that have generally been considered a consequence of diseases such as Alzheimer’s. Now researchers are looking into whether sleep problems might themselves be a risk factor for cognitive decline, dementia, and Alzheimer’s. In a recent study funded by the National Institutes of Health, it was found that losing just one night of sleep led to an immediate increase in beta-amyloid in the brain. These beta-amyloid proteins clump together to form the amyloid plaques that impair communication between neurons and are a hallmark of Alzheimer’s disease. While previous studies have shown that sleep deprivation elevates the level of beta-amyloid proteins in the brains of mice, this is one of the first to show that sleep may play an important role in clearing beta-amyloid in the human brain. This is an important step in helping us understand the pathology of Alzheimer’s and potentially how to prevent it.

Reversing cognitive decline

We are seeing more and more evidence that sleep plays a critical role in maintaining brain function as we age. The question of reversing cognitive decline by improving sleep is another interesting avenue for investigation. A 2014 study tested a novel therapeutic program for reducing mild cognitive impairment based on the idea that clinical trials in pursuit of a “magic bullet” drug have yielded little but that a combination of therapies that address multiple targets in the underlying pathology of Alzheimer’s might have an additive or synergistic effect. The program included life style changes, including sleep optimization, as well as a regimen of medication and supplements designed to optimize metabolic factors implicated in Alzheimer’s, correct imbalances, reduce beta-amyloid, and more. The study was small but showed impressive results. Clearly this combination approach shows promise.”

Improving sleep

Everyone has trouble falling asleep occasionally. For most of the millions of Americans who regularly struggle to get to sleep or stay asleep, improving sleep habits can restore a restful night’s sleep. Here are my recommendations:

• Don’t eat a heavy meal or drink a lot of liquid close to bedtime. Reduce or eliminate stimulants such as caffeine and nicotine during the day and alcohol in the evening.
• Exercise regularly – but early in the day, not within several hours of bedtime.
• Stick to a sleep schedule, going to bed and waking at the same time each day, including weekends. Avoid naps or limit them to 30 minutes; don’t nap after 3:00pm.
• Keep your room cooler than during the day. Use a fan or noise machine to mask distracting sounds. Try room-darkening shades if morning light wakes you too early.
• Take about 30 minutes to wind down before going to bed. Do something relaxing, like reading or listening to quiet music. If you can’t fall asleep after 20 minutes, do something relaxing for 20 minutes, or until you feel sleepy.
• Sleeping on your side, particularly on your left side, may improve circulation while you sleep.
• Don’t use a computer, tablet or smart phone right before going to bed! The light from the screen stimulates the brain and makes it hard to fall asleep.

We’ve long known that sleep is important for overall health and especially for brain function. Now, as we uncover the mechanisms at work, we have the opportunity to make great strides in preventing and treating cognitive decline and degenerative disease.

Alex Dimitriu, MD, is double board-certified in psychiatry and sleep medicine and is the founder of the Menlo Park Psychiatry and Sleep Medicine Center in Menlo Park, CA. http://www.doctoralex.com