Sleep is one of the most important activities we do. We spend roughly a third of our lives asleep, and for many of us, we spend plenty of time while we’re awake THINKING about sleep. But how are sleep and cognition connected? Let’s find out…
The exact amount of sleep each person needs depends on a number of factors including age, physical health, and even genetics. We’ve all heard that we need about 8 hours of sleep every night to be ‘fully rested’ but the truth is, the recommended amount of sleep varies greatly as we age.
HOW MUCH DO WE REALLY NEED?
While adults and seniors typically require between 7 and 9 hours of sleep, school-aged children and teenagers require slightly more sleep, anywhere from 8 to 11 hours daily. The amount of sleep recommended is even higher for preschool-aged children and toddlers – from 10 to 15 hours per day. Newborn babies require the most sleep of any age group, with recommended sleeping times as high as 17 hours per day or more.
To understand the exact amount of sleep you need each day, you should evaluate your overall health, sleep patterns, and the types of activities you do.
If you feel that the amount of sleep you are getting isn’t enough to get through the day, you may want to spend a little more time in bed. Also, you might want to consider whether or not you are relying heavily on caffeinated drinks to get through the day, as this can be a sign that you aren’t getting enough healthy sleep during the night.
WHAT HAPPENS IN OUR BRAINS?
When we fall asleep, we go through a number of sleep cycles consisting of a few distinct stages of sleep. These cycles typically last between 60 and 120 minutes each.
There are 4 stages of the sleep cycle, broken up into two groups: NREM and REM sleep. The first three stages are NREM, or Non-Rapid Eye Movement sleep, while the fourth stage is REM, or Rapid Eye Movement sleep.
When we first fall asleep and enter into the first stage of NREM sleep, our brain begins to slow down, and our body with it. We begin to breathe more slowly, our heart rate drops slightly, and our muscles begin to relax.
As we fall deeper into sleep, we move into the second stage of NREM sleep where our body becomes less aware of our surroundings and our core body temperature drops. In this stage, the brain begins to release rapid, rhythmic bursts of brain wave activity known as sleep spindles.
The next stage we enter is the third and final stage of NREM sleep, but it is also the first stage of what is referred to as ‘deep sleep’.
During this stage our body and muscles become completely relaxed, blood pressure continues to drop, and our breathing slows. It is during this stage that the body accelerates the physical repair processes throughout the body and increases memory consolidation in the brain.
When we continue further into the ‘deep sleep’ stages, we enter into the fourth and final stage of the sleep cycle: REM sleep.
During REM sleep our muscles become completely immobilized, our breathing and heart rate begins to rise, and our eyes begin to move around quickly. It is during REM sleep that we really begin to dream. This is the time when the brain focused on saving and organizing information into long-term memory as well.
WHAT HAPPENS WHEN IT’S NOT ENOUGH
When we aren’t able to get enough healthy sleep, our body quickly begins to experience the effects of sleep deprivation. Whether we experience mild sleep deprivation from missing a few hours of shut-eye or more extreme sleep deprivation from habitually poor sleep, we will see adverse changes in cognitive and physical performance.
First and foremost, extreme sleep deprivation impairs attention and working memory but it also affects other functions, such as long-term memory and decision-making. In addition to this, even with mild sleep deprivation, we can begin to see effects on general cognitive functions such as attention.
HOW CAN WE GET MORE SLEEP?
Our ability to fall asleep and stay asleep can be affected by many things.
Consuming stimulants such as caffeine or medications can cause us to have difficulty falling asleep, but consuming alcohol or other depressants can make it difficult for us to stay asleep or reach the regenerative deeper levels of sleep. All aspects of our diets can affect our sleep including chemicals such as tryptophan, melatonin, and even sugar.
Another aspect of our lives that greatly impacts the quantity and quality of our sleep is how active we are throughout the day.
Spending more time doing activities such as playing sports, working out, or even walking can make it much easier to maintain a healthy sleep schedule, though doing these activities right before bedtime can make it difficult to fall asleep due to an increased heart rate and adrenaline.
In addition, setting and sticking to a schedule can help your body prepare for sleep better and wake up feeling more rested.
Your body’s internal clock can help relax your body and prepare for sleep by releasing chemicals when it is ready for bed. When you have a set schedule your body can better predict when it is time to go into ‘sleep mode’ and waking up at the same time every day can help your body better schedule the sleep cycles so that you are in a lighter stage of sleep when your alarm goes off in the morning.