The Importance of Sleep
We’ve all heard before that sleep is important and we need about 8 hours of it a night, but we don’t really take any notice of it. Most of the time going to bed is often an inconvenience that we delay because it’s getting in the way of things, like on a night out with mates, or if you got home late from work and want to go to the gym, have some food, and chill out watching TV before getting into bed. The only time we think about sleep is when we are setting the alarm clock to get up in the morning, and thinking how much of a lie in we may get on a weekend. So this blog’s aim may be futile, but it’s an attempt to highlight the importance of sleep and to try to get everyone striving for more of it.
What we do know about sleep is that it is probably the single most important behavioural experience we do. The average person spends 36% of their life asleep. So if you live to be 90yrs old, then you would have spent 32 years asleep.
Robert Stickgold is one of the world’s leading researchers on sleep, and says “we understood the biological functions of the sex drive, hunger and thirst two thousand years ago, but for sleep we didn’t know much about it a dozen years ago, so the first thing I would suggest is that its subtle,” he says. Nonetheless: “If you don’t sleep, you die. The rat experiments are very clear, but after twenty years {of studying this} we don’t know why the rats die. Cause of death unknown.”
One thing that Robert Stickgold’s studies have shown is the link between disease, mental illness, memory, obesity and sleep deprivation. Which by the way most of us probably suffer from without even realising. Getting the right amount of sleep, hydration and exercise are three seriously big health factors that the majority of the population are constantly deprived of. Put in simpler terms Stickgold says “if you don’t get enough sleep, you are going to end up fat sick and stupid.”
Stickgold says, the Iraq war was pretty unique for a variety of reasons, but mostly because it was predominantly a night and air war. Basically American technology allowed complete command of the dark, and because of that a lot of sleep was lost which has now prompted a great deal of research by the military on sleep. We now understand that one of the consequences of sleep deprivation is craving very dense carbohydrates and sugars. Hence the reason Stickgold says the Iraq war was really run on snickers bars.
On his sleep resistance tests he gave college students 4 hours of sleep for four nights in a row. His results mirrored others, which showed that the body’s ability to clear glucose out of the blood went down by 40%, and the acute insulin response went down by 30%. Basically these students after four nights were starting to look like people with type 2 diabetes, as insulin regulation was on the decline, and the body was storing more glucose as fat. Sleep loss was also triggering the hormone ghrelin, otherwise known as the hunger hormone, meaning not only were subjects storing more fat, they were craving more carbs and sugars – hence the military and their snickers crisis.
Lack of sleep also seems to wreak havoc with your immune system. Researchers gave volunteers, some who were sleep deprived of a few hours a night for just a couple of days, a hepatitis C vaccination. The group with less sleep produced 50% fewer antibodies in response to the vaccine, than the control group. Showing that sleep loss has a direct impact on the immune system, and this is what Stickgold meant earlier when he said that the effects of sleep was subtle. Most of us would never notice a comprised immune system, and most of us would never associate that cold with a lack of sleep.
Mental illness and depression have also been physically linked in the brain, with genes that generate sleep are always mutated when seen in individuals with mental health problems – bi polar and schizophrenics as examples.
Researchers also found that on a simple test of recall, people who were sleep deprived and were shown lists of images with a clear emotional content, like pictures of cute little puppies and images of war, all mixed up with positive and neutral ones too, had problems with recall. Which is to be expected but not however with the negative images – they only had problems with the positive and neutral ones – which is a slam-dunk to a link with depression.
Most businesses are now cottoning on to the fact that sleep is just good for business. Companies like Google, Nike, Proctor and Gamble, Cisco Systems and others have begun allowing employees to take naps at work to enhance productivity and creativity. It’s just common sense, but there’s still the stereotype of the committed, hardcore, keen and reliable worker who only sleeps 4 hours a night and works all around the clock to meet his deadlines. This is a dangerous stereotype that needs to be changed, it was Margaret Thatcher who used to say “Sleep is for wimps”, but the reality is the people working twenty hour days probably need to, because they are probably doing everything twice, as sleep loss is making them slow and inefficient.
Stickgold’s many experiments have shown how memory and learning is improved 10 fold with sleep. It’s the process of sleep that lays down and interprets new memories and completes the learning process. Experiments where groups try to memorise lists of words, one group was shown the list in the morning and tested at night without sleep, compared to being shown a list in the evening and tested after sleep the next morning. All experiments and tests are conclusive in the results which show staggering differences in the ability to remember much more after sleep.
What is being discovered is that for every two hours you are awake, you need an hour of sleep. The brain needs to process memories and experiences from the day and decide what to keep and what to throw away. As Stickgold says, you can’t think internally whilst taking in new information at the same time. For example, if you are having a conversation with someone and they are talking to you – you can’t think about something else whilst computing every word that they are saying. So evolution has figured out a way to compute and retain all the information we required throughout the day, by taking us offline during the night. To shut us down so we can process the information.
There are many stages to the sleep cycle – four stages of NREM sleep – which is non-rapid eye movement sleep, followed by REM sleep (rapid eye movement). This five step cycle repeats many times throughout the night with each REM stage getting longer and longer. Meaning that the dream state (REM stage) gets more intense latter on in the sleep cycle.
Stage 1 is between being awake and asleep
Stage 2 is the onset of sleep, being disengaged from surroundings, body temperature starts to drop. HR and breathing still regular
Stage 3 & 4 is the deep restorative sleep where muscles are relaxed, breathing slower, blood supply to muscles is increased, tissue growth and repair happens, Growth hormone released.
REM Sleep – Occurs typically after 90mins of sleep, and recurs after every 90mins getting longer each time. It’s the dream state. Muscles are completely paralysed so you don’t act out your dreams and injure yourself. The brain is more active here than it is during the day.
The dream state is believed to be part of the process for laying down and storing memory – where it plays back and re-enacts subconscious thoughts and memories either to lay them down as memory or to find a better way of using the information, or throwing it away. For example, many tests with rats have shown how when put into a maze marked with areas of chocolate, certain neurons fire up in the hippocampus, which is involved in memory and space, when they are in those places. When the rats then sleep, these same neurons (also called place neurons) fire up when they are sleeping/dreaming. Meaning the brain is playing back information it deemed important to learn/remember – especially as it had direct links to food/chocolate. The next day the rats found the same route without any trouble, and what’s also been seen is during sleep, the rats ‘place neurons’ fire in a different order as it processes a shortcut not taken by the rat. The next day the rat took the shortcut, that had been decided and worked out by the brain whilst it was asleep.
This study with the rats shows how the saying that ‘you should sleep on it’ when you are undecided with a decision actually has some legs.
So we sleep in discrete stages, each marked by clear and distinctive patterns of brain activity, with some of these stages correlating with specific benefits be it to the brain or body. If you deprive someone of one of these stages, the benefits linked to that stage do not accrue, even if the total sleep is over the golden average of 8 hours per night.
In REM sleep that are some interesting facts about dreams and the individual specifics of them. We are more likely to have aggressive dreams about being chased or being threatened than having a sunny day with rainbows and butterflies. In the aggressive dreams the attacker tends to be male or a group of males, or an animal.. for both genders.
The analysis gets a bit more interesting in the case of children, where the scary element tends to be overrepresented as animals. The type of animal tends to be more wild as well, and not dogs, cats, and horses - more like gorillas, lions, snakes and spiders.
As the children move towards adulthood the animal content in their dreams tapers off, and this is true of all cultures as they all adjust their dreams to the realities of their world.
What is very interesting is the studies done on children who have never seen a wild animal before in real life or in books or TV, and have therefore had no reason to fear an attack by one. They have dreams/nightmares at an early age involving those never seen before animals, which suggests something quite innate, a hardwired memory of conditions more realistic in evolutionary time, when children and adults both had every reason to fear animal attacks.
Studies have also been done on modern day hunter gatherers like the Aboriginals in Australia and with the Mehinaku Indians of central Brazil, before they had significant contact with the outside world. They both dreamed about wild animals far more often than civilised humans did, but at about the same rate of civilised children, indicating that the decline of animals in dreams as we age, is indeed an adjustment to our civilised world. We enter the world programmed to dream of the wild, but civilisation takes those dreams away. These dreams though aren’t just random, they serve a purpose as a rehearsal of challenging events to allow the brain at night to prepare the individual on the reactions and skills necessary to function in the environment with our most important threats – an instinctive and necessary part of our survival mechanism.
All plants and animals on Earth developed their own biological clocks to deal with light and dark – night and day. We have this ability too and we call it the body clock. Test have shown if you take someone’s watch away from them and lock them in a bunker with no light for a couple of months (people actually volunteer for this) they get up pretty much on time every day, give or take 15mins, which shows they are working on their own body clock without any external factors from outside.
Now, our natural body clock if allowed to work normally without any artificial light at all, sees subjects sleeping twice every night, they go to bed at about 8pm until midnight and then sleep at 2:00am until sunrise. This waking midway time between sleeps historically was a time of rest, used for reading, writing, smoking, praying, having sex or visiting the neighbours as noted in 15th century England. It was only when Thomas Edison created the light bulb, and street lighting became common practise with coffee houses staying open late, did we see the demise of the second sleep. Records and people who sleep the natural way of the body clock which involves two sleeps, describe a wakefulness during the day that they’ve never felt before. This is perhaps also down to the production of hormones, like prolactin for example, that is produced only during this natural cycle of sleep, that modern day users don’t get the benefit of.
However, the second sleep is not something that we can all afford to do as going to bed in the winter in the UK when it gets dark to follow our natural body clock, would mean falling asleep at work at 16:00! But what we can realistically do is get to bed early enough most nights to get the 8 or so plus hours needed for optimum health and brain function. As discussed the act of sleep stabilises and enhances new memories, it then integrates new and old memories to rewrite and update our behaviour – creating new meanings and instincts. It’s also where hormone and immune function is regulated and controlled, along with clearing toxins from the brain and mood regulation.
So bed at 10ish and up at 6/7ish will make sure you don’t get stupid, unhappy, fat or sick.
References:
Go Wild - John J Ratey & Richard Manning
Russell Foster - Why Do We Sleep
Robert Stickgold - Youtube Clips/Ted Talks
Mystery of Sleep - Documentary Netflix
Jessa Gamble - Our Natural Sleep Cycle