Cognitive decline is when a person begins to experience slight but noticeable changes to their mental functions such as memory and thinking skills. A recent study has revealed a ‘sleep sweet spot’ that helps to retain stable cognitive functioning.

Led by researchers at the Washington University School of Medicine in the United States, the study monitored the sleep of 100 older adults over a number of years. It found that those who slept six to eight ours were able to maintain stable cognitive functioning. This is the sleep sweet spot. (Read more about the study here.)

Those who slept fewer than six hours or longer than eight hours showed declining brain function. This suggests that it’s not necessarily about how much or how little you sleep, but rather the quality of your sleep.

Alzheimer’s contributes to a large percentage of dementia cases, and is the main cause of cognitive decline in adults. Poor sleep is a common symptom of the disease and is also known to speed up the decline.

The sleep sweet spot requires continual, quality sleep

The sweet spot for sleep is six to eight hours of uninterrupted sleep, where you are able to cycle through the various stages of sleep four to six times each night.

• Stage 1– During the first stage of sleep, your body starts to relax. Bodily functions such as breathing and heartbeat slow down and your muscles relax and your brain waves begin to slow down.
• Stage 2– This stage encompasses half of your sleep cycle. You fall into this stage of sleep more than any of the others. During this stage your body continues to relax, your brain waves are much slower with short periods of activity, your eye movements stop and your body temperature drops.
• Stages 3 and 4– These stages are considered deep sleep stages.  This is where your body is in the deepest state of relaxation and brain waves are at their slowest.  At this stage, it’s hard to wake up, and you might not even wake up with loud noises. Your body stays in deep sleep the longest during the first few cycles.  As the night progresses the deep sleep cycle gets shorter.
• Stage 5– This last stage is REM (Rapid Eye Movement) sleep.

Sleep stages 3 and 4 facilitate several processes in the body.  During these stages, the brain metabolises glucose which helps with memory and overall learning.  As you sleep, your brain forms new neuropathways, which helps with learning, remembering and problem-solving.  These are the other benefits of deep sleep:

• Promotes growth and repair of tissues and bones
• Cells regenerate
• Strengthens the immune system
• Increases blood supply to the muscles
• Restores energy

Deep sleep is a vital part of your body and your brain healing itself

There are many things that can cause you not to fall into sleep stages 3 and 4.  One of the main contributors is your mattress. When your mattress is not comfortable, it’s difficult to fall into a deep sleep because your body can’t get comfortable enough to relax.  You may toss and turn which keeps your body alert.

If you are waking up tired all the time, even after getting the right amount of sleep, you might need to look at your mattress as the culprit.  A good mattress supports your body and allows it to relax and fall into a deep sleep. Use the Sealy mattress selector tool to help figure out the best mattress for your needs.

Below are some additional tips that will help you hit that sleep sweet spot, to get the sleep your body needs:

• If your sleep is suffering, seek professional help as soon as possible. Please note that this article, and any information provided on the Sealy blog, is not intended to be a substitute for professional medical advice, diagnosis or treatment.
• Be mindful of the media you consume, especially close to bedtime. Reading bad news might make you feel anxious, which will hinder your sleep.
• Try get outside into the sunlight the first one or two hours after waking up. This helps to set your circadian rhythm.
• Create a calming bedtime routine which you start at least 30 minutes before bedtime.
• Stick to the same bedtime and waking up time. Your body, and your sleep, responds well to routine.
• Try to clear your mind by journaling and meditating.
• Fit exercise into your day but be careful not to exercise too close to bedtime.