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Counting Sheep - 10 Facts about Sleep

Thursday 6 April 2017 4:13pm

For our first brain week lecture of 2017 Dr Celia Lie and Regina Hegemann from the department of Psychology at Otago guided us through ten important facts about sleep. The ‘why’s, the ‘how’s, and the ‘what if’s of a behaviour that takes up a third of our lives.

1. Everyone sleeps

The three pillars of health are built on nutrition, exercise, and sleep. This is true of almost every animal known. How much sleep we need seems to be rooted in our evolutionary history. Generally, predators sleep the most, and prey sleep the least. Fish sleep while moving, and dolphins sleep with one side of their brains at a time. What we know is that sleep, or a sleep-like state, is a necessary part of life for all animals, from the smallest frogs to the largest whales, we all sleep.

polarbear sleeping

2. The brain is always awake

Unlike a computer, when we go to sleep our brains stay active. Psychologists describe sleep not as a loss of consciousness, but as an altered state of consciousness. We aren’t consciously aware of the world around us, but our brains are still processing external information. We know how far we are from the edge of the bed, or from other people in our beds, and we’re able to wake up if something unexpected happens, like an earthquake or a smoke alarm going off. The brain never really takes a break.

3. How do we get to sleep? And what is the brain doing while we’re sleeping?

There are two groups of neurons in your brain that are important for sleep: Arousal inducing neurons, which keep you awake, and sleep promoting neurons which turn off the arousal inducing neurons. The longer you go without sleep the stronger the pressure on the arousal inducing neurons to turn off, and once they do turn off you find yourself slipping to sleep.

Once you’re asleep your brain enters into a series of sleep cycles designed to clean, repair, and strengthen connections. These cycles shift between REM-sleep (rapid eye movement sleep), and non-REM sleep.

4. Do our dreams mean anything?

Dreams are audio and visual hallucinations which can occur at any point during sleep, but the stage at which they occur will impact what the dream is about. Dreams during REM sleep tend to be both highly vivid and bizarre as the emotion and reward centres of the brain have increased activation. During non-REM sleep we are less likely to have these vivid dreams. For those who can remember their dreams, themes start emerging. Dreams about school, sex, falling, and being chased are among the most common, but why we dream of these things and what they mean? We just don’t know.

falling dream

5. Why do we sleep?

We sleep to learn and to heal. Different stages of sleep help us to do this in different ways. REM sleep regulates emotionally significant memories, memories of how to do things, and creative ways to deal with problems. Non-REM sleep helps to sharpen your memory for events. This is all achieved by strengthening specific connections in your brain, and breaking others in order to create space for new connections to be formed.

6. Rest and repair during sleep

Repair is the other side of sleep. REM sleep repairs the brain and replenishes energy stores, while non-REM sleep allows the body to repair by boosting growth hormones and the immune system. While you’re awake your brain cells push all of their waste into the space between cells, once it builds up this waste can make it hard for cells to communicate. During sleep your cells shrink down and allow fluid to pass around them, washing away that waste and allowing your brain cells to work more effectively.

7. What happens if we don’t sleep?

If you don’t sleep none of those good things have a chance to happen. The space between your brain cells becomes cluttered with cellular waste, making it harder to think, pay attention, and keep information in your short term memory. Your immune system begins to suffer, stress rises, and it becomes difficult to regulate your emotions.

8. Catnaps

So, if you can’t get a full night sleep, what can you do to help your brain and body survive? Have a catnap. These naps, usually in the middle of the day, reduce blood pressure, boost your immune system, and can improve cognitive function. But how long is long enough?

If you can’t spare much time but you need a little break then 6 minutes may be enough. With a 6 minute catnap you can improve some aspects of your cognitive functioning, but not much else. A 20 minute catnap starts to give you some of those physical benefits, improving your heart rate as well as your general mood and alertness. 40 minutes will get you through a stage of REM sleep, increasing your awareness and giving a little boost to your immune system. These longer naps will have further benefits but there may now be some ‘sleep inertia’ which may make you feel a little groggy when you wake.

9. Sleep changes throughout life

coffee yawn

The amount you sleep, and when you sleep, will change throughout your life. As infants we sleep for around 16 hours a day but, as parents will already know, not all at once. As we age we need progressively less and less sleep. When we go to sleep is determined by when our body naturally releases the hormone melatonin, which stimulates our sleep promoting neurons to turn off our arousal inducing neurons. In teenagers melatonin is released later, causing them to sleep and wake later than children or adults. The elderly, on the other hand, have melatonin release earlier and so they experience the opposite, typically sleeping and waking earlier than

other groups of people.

These shifts are natural, but they can be difficult to adjust to. The adjustment is especially difficult for the elderly, as their window for sleep appears to be much smaller. This means that if they wake in the night they will find it much more difficult to get back to sleep.

10. How to get a good night’s sleep

If sleep is so important what can you do to make sure you can get to sleep, and stay asleep all night? Maintain healthy sleep hygiene. Like physical hygiene, sleep hygiene is all about routine. So here are some tips for keeping that routine focused and healthy:

  1. Don’t drink caffeine or alcohol before bed
    Caffeine is a stimulant which will stop your brain from being able to put you to sleep. Alcohol, on the other hand, is a depressant. This means it can make it easier for you to sleep, however the sleep you have will not be restful as alcohol also interferes with your sleep cycles. Having neither in your system will make for a better, more restful, nights sleep.
  2. Stop looking at screens half an hour before you want to sleep
    The light from your computer or tv screen supresses the release of melatonin. As we noted above, melatonin is the hormone signal that starts to put you to sleep. If melatonin isn’t released it can be very difficult to get to sleep.
  3. Beds are for sleeping
    Your brain is very sensitive to associations. You know that your bed is a place to sleep, but if you spend your whole day there then your brain will associate it with being awake. Try to minimise the amount of time you spend awake in your bed. That way once you get to bed your brain will know exactly what to do. This means that if, for instance, you can’t sleep you should go somewhere else until you’re ready to try agai
  4. Keep a consistent sleep schedule, even on the weekends
    Sleeping in on the weekend can be a real luxury, but it may also be making it harder to sleep on weeknights. Having a consistent schedule can make it much easier for your brain to know when to wake and when to sleep. This may be the most difficult tip, but it is well worth the adjustment.

We hope you’ve found this article helpful. Now, go get some sleep!

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