Processing experiences; storing facts; filtering thoughts; strengthening important connections; pruning insignificant connections; refining memories; repairing damaged tissues; growing cells; building muscles; and synthesising hormones; Sleep can be a full-on sensory experience. From the outside it might look like we’re merely resting. Indeed, a crucial process of restoration and recuperation is occurring but our conscious self and physical body need to be otherwise occupied so that this and other vital work can take place.1 Beneath the apparent outward stillness of sleep, the body and brain are busy cracking on with some life maintaining and life changing processes. Sleep is anything but motionless.
Why do we sleep?
“Sleep is that golden chain that ties health and our bodies together.”2 It’s essential; and paramount to our physical and mental well being. We are thinking, feeling, sentient, communicative, creative, learning, changing, growing, working, active, doing beings; sleep helps us to be this.
- Brain: Our brain needs sleep in order to function properly. When tired, the brain begins to lag, reactions are slower, concentration doesn’t come easy and we are more likely to lose control emotionally or react irrationally when we haven’t had enough sleep. This is all completely natural, because sleep is crucial to cognitive function. Processes such as speech, memory, reaction, intellective and originative thought are all given a new lease of life. While we sleep the brain is able to recharge just like the body does. Essential brain development occurs and memory processing takes place.
- Body: Our body needs sleep in order to rest but also to carry out vital building, repairing, growing and restorative work. In addition to this, important physical, metabolic, hormonal and biological processes occur while we’re asleep. Although we need sleep to recharge us physically it’s interesting to note; when we sleep for a stint of 8 hours, we only save about 50 kCal energy wise. This makes it even more apparent that we sleep for reasons beyond physical rest and revival.3
- Benefits of sleep?
- Sleep is certainly more than just taking a snooze. It provides a multitude of functions and benefits for both body and brain.
- Physical maintenance: A whole host of vital physical, biological and metabolic processes occur when we sleep. Sleep gives our bodies the chance to rest, grow, build, repair and rejuvenate.
- Energy and Vitality: Sleep helps us to go about our daily lives with enough energy and vitality to achieve what we need to physically. Sleep helps to keep us healthy in body, spirit and mind.
- Cognitive ability: Sleep has been described as “nutrition for the brain.”4 Our minds need sleep to function properly and to carry out a range of cognitive functions. Sleep assists cognitive ability in a number of ways. It can help our ability to think on our feet, concentrate, retain and recall information, think logically and string a sensible sentence together. Sleep is essential for our brain to cope with tasks that require eye-hand coordination, for example.5 Sleep helps us to function properly, so we can be communicative, decisive, productive and efficient. Lack of sleep essentially dampens brain activity in the brain’s frontal lobe; the part responsible for making decisions and controlling impulses.6
- Memory consolidation: Studies have indicated sleep can specifically affect how our memory functions. In recent years interest has focussed on the role of sleep in memory consolidation. For example, research shows that sleep deprivation affects our ability to learn and recall ‘episodic information’ which means the brain can struggle to digest information consisting of a series of separate parts, events or facts; When we get enough sleep; our ability to retain and recall episodic information improves considerably.7 Studies also show that getting enough sleep the night before, can promote our ability to understand, learn and digest new information the following day.8
- Emotional balance and perception: Our minds need sleep to carry out a range of emotional processes. Studies have indicated that our brains are much better equipped to encode ‘emotional’ memories in a balanced way if we’re getting enough sleep and that this crucial emotional coding occurs while we sleep. Sleep helps us to remain rational and rooted in ‘reality’ and perspective. If we’re deprived of sleep, we run the risk of existing in a misshapen reality where the memories formed and maintained tend to be negative rather than positive; even when experiences during waking hours are a balance of positive and negative.9 Interestingly, when we’re sleep deprived our perception of pain is increased, so getting enough sleep can also help us to feel less pain physically. This is also true of emotional perception and therefore how we react to emotional pain is affected by how much sleep we get.10
- Emotional encoding: Sleep allows the brain to consolidate experiences, filter memories, encode thoughts, form associations and integrate emotional attachments. Sleep allows us to process recent emotional experiences referred to as ‘emotional-memory’ processing which is paramount to the process of emotional encoding and plays a big part in how we form personal attachments. Research in recent years has indicated that sleep has a major role to play in the “ability of the human brain to generate, regulate and be guided by emotions” representing a “fundamental process governing not only our personal lives, but our mental health as well as our societal structure.”11
- Mood: Sleep helps our mood. It helps us to cope with the daily emotional experiences of being human. It stands to reason that lack of sleep can contribute to feelings associated with depression and other affective mood disorders. Getting enough sleep can go a long way to to alleviating symptoms associated with a range of mental health conditions and mood disorders.12.
- Heart health: Sleep is crucial to maintaining a healthy heart. When we sleep our heart has a chance to rest too. Blood pressure and heart rate decrease which means the heart gets to take a break from working so hard.13 Further to this; when we get enough sleep, essential functions, such as the metabolism of glucose, the production of hormones and various cardiovascular functions have the right conditions to take place properly. Lack of sleep and disrupted sleep can adversely affect such biological and metabolic processes, causing problems with blood pressure and inflammation, for example, illustrating just how serious sleep deprivation can be in terms of increasing the risk of cardiovascular disease.14
- Immune system: Getting enough sleep helps to maintain a healthy immune system. Lack of sleep can impair the immune system and interfere with vital processes meaning we’re more likely to get unwell.15
- Weight: Maintaining a regular, healthy sleep pattern can help promote healthy weight management:
- Lack of sleep can actually increase cravings for food. A hormone called Ghrelin is produced to tell the brain we’re hungry. When deprived of sleep, the body produces more Ghrelin so we tend to feel hungry and eat more. We also produce a hormone called Leptin which tells us when we’ve eaten enough food. Lack of sleep causes Leptin levels to drop which tells the brain we should eat more food.
- This chemical process, coupled with the brain’s inability to make logical decisions when tired, means we’re more likely to comfort eat, as our brain looks for something to make us ‘feel better.’
- Research has also shown that we are more likely to crave ‘junk food’ high in carbohydrates when we’re suffering from lack of sleep and in addition to this we tend to eat larger portions when tired.
- Getting enough sleep ensures we have a healthy metabolism. Lack of sleep affects how our body reacts to the production of insulin. Insulin is required to convert sugar and starches into the energy we need to fuel our daily lives. When deprived of sleep our bodies can’t properly process the fats present in the bloodstream so they end up being stored in the body as fat. In addition to this, when we’re tired the body produces more Cortisol, a stress hormone which tells the body to save energy, ie store fat, to fuel the increased hours that we’re awake.
- Further to all of these factors; while we’re piling on the calories we’re also less likely to exercise when sleep deprived because we’re feeling tired and lacking in energy. It’s clear to see, on many levels, how getting enough sleep is intrinsic to maintaining a healthy weight.16
Just how much is ‘enough’ sleep?
The average adult should be getting between 7-9 hours sleep a night in order to function properly and to maintain optimal mental and physical health. Babies need about 16 hours sleep a day. By the time we reach our teens we need less sleep; on average 9 hours a night. 17
What can a lack of sleep do to us?
Sleep affects pretty much every aspect of being human. Insufficient sleep leads to a variety of dysfunctions. Simply put; lack of sleep slows us down; physically and mentally. If we’re continually depriving ourselves of sleep our body and brain will eventually let us know that something isn’t right. Normal functioning begins to go on strike while our immune system and cognitive ability is affected from lack of sleep. Studies have shown that a lack of sleep can seriously increase the risk of a range of health issues including heart disease, heart attacks, diabetes, and obesity.18 The bottom line is; sleep is essential for good health of both body and mind and without it both would cease to function properly and eventually break down.
What induces sleep?
What helps us to feel sleepy at the right time to enable our brains to change from an active state of alertness to a state conducive to sleep? It’s all riding on rhythms and chemicals. Our bodies keep track of when we need to sleep with the help of chemicals which are produced to monitor our wake/sleep cycles and identify how long we’ve been awake for; while others help us to feel drowsy and to feel like we ‘want’ to fall asleep at about the right time every day. These chemicals work with other chemical processes and outside factors, such as temperature and sunlight, which tune our bodies and brains into feeling tired at the appropriate and optimal time to sleep. When the cells in our eyes pick up sunlight, a chemical called melanopsin is produced which helps us to know it’s daytime and in turn to feel aware, alert and functioning in ‘wake’ mode. As the day draws to a close and the light begins to fade, so too does the amount of melanopsin produced in our eyes and instead, when it gets dark, our bodies produce a chemical called melatonin which tells our bodies it’s the right time to rest. This whole interactive and multi-faceted process is slowly smoothing the way for sleep. Our brains are essentially withdrawing from the external reality we inhabit and entering the internal world of sleep.19
Our bodies work within natural rhythms and cycles and our sleep cycles are affected by and an intrinsic part of our natural ‘body clock’. The human body clocks usually operates on a 24 hour repetitive cycle known as the circadian rhythm which works in sync with and reacts towards certain external factors such as light and darkness, helping our bodies to distinguish between day and night; awake and sleep timings. Throughout the daylight hours our bodies go through a process of naturally moving towards sleep. This natural momentum or impulse towards sleep slowly builds until the point at which our internal body clock tells us we’re sleepy and ready for bed. A chemical produced by the brain called adenosine, is believed to be linked to this natural momentum towards feeling sleepy. During our waking hours the brain produces adenosine at a rate which increases throughout the day, reaching a pinnacle at the point that we would usually fall asleep. While we sleep, the levels of adenosine in the body are diminished and when we wake the whole process begins again. In the morning as the day begins and the sunlight takes over from the night, our bodies produce a chemical called cortisol which helps us to physically and mentally switch to ‘wake’ mode.20
Our body clocks adapt as we grow and change throughout our lifetime. In tune with this, the amount of sleep that we need as individuals changes too as we grow older. Teenagers not only want to go to sleep later than their younger siblings and parents, they are actually guided by chemical processes. During teenage years melatonin is produced at a later stage in the circadian cycle to that of young children and adults which means teenagers tend to feel sleepy later. This also accounts for the archetypal lie-in teenagers are so famed for.21
Phases of sleep
We experience different phases of sleep which operate on a repetitive rhythm throughout the night. There are essentially two stages of sleep; and within these stages are various phases:
- Stage 1: Rapid Eye Movement (REM) sleep - Eyes shut, brain waves start to get slower. This stage consists of alpha-activity, where we’re awake but just about to drop off, then slowly moving between alpha activity and theta-band activity, as we begin to fall asleep.
- Stage 2: Non-Rapid Eye Movement (non-REM) sleep - the transition between wakefulness and sleep. During this stage brain waves are shifting between alpha activity and theta-band activity until the alpha activity finally lets go and we fall asleep.
The cycles flow through various levels of non-REM sleep then into REM sleep and then returning to non-REM sleep . Each complete cycle usually lasts between one to two hours.22
As well as patterns of sleep changing as we grow older, the nature of the sleep we get also changes as we age. Young babies will experience a great deal more REM sleep than elderly people, for instance. In childhood we also go through a specific phase of non-REM sleep called slow-wave sleep, deep sleep or delta-band activity, more than in adulthood. Once we hit puberty we begin to experience less and less of this stage of sleep and it continues to drop as we continue to age.23
Sleepy tricks of the trade - Lifestyle tips for sleeping
Once our body clocks have found their own rhythm and sleeping patterns are established we should all be experiencing amazing nights of long, uninterrupted sleep, right? Unfortunately for a huge proportion of us this simply isn’t the case. According to a survey conducted in 2012, 51.3% of us here in the UK regularly experience difficulty sleeping.24
There are some simple changes we can make to help us get a good night’s sleep.
- Switch off: Exposure to bright artificial light in the late evening can make it hard for our brains to switch off when it’s time to fall asleep, making it tricky to fall asleep. This type of light is usually generated from a TV screen, computer screen, tablet or phone. So switching off gadgets a good couple of hours before we want to fall asleep is a good start. Switching the light off while we are trying to fall asleep will also help. Light disrupts the production of melatonin, the hormone that tells our bodies it’s the right time to sleep. While darkness encourages the production of melatonin, encouraging us to fall asleep.
- Stop trying so hard: Trying to fall asleep is a bad place to start. Just thinking about falling asleep can stop it from happening. When we fall asleep, this is often the point at which our brains begin to process the day’s events and worries that may be niggling. Trying to think about something non-emotional while diverting thoughts from the act of falling asleep should help us to nod off in no time.25
- Daily exercise: Getting an adequate amount of exercise can ensure we sleep well.
- Relax: Try doing something relaxing before bed, such as listening to calming music, taking a gentle stroll, reading a book, having a bath or meditating.
- In tune: Try listening to your body clock and go to sleep when you’re feeling tired at night.
- Routine: Creating a bed ‘time’ that you stick to can help too. The daily routine of going to bed and waking up at the same time can help set a healthy sleep pattern and promote good sleep.26
- Avoid caffeine: Don’t consume caffeine late in the day. Caffeine is a mental and physical stimulant and is best consumed in the morning so that it has time to pass through our system before bedtime. This means avoiding coffee, tea, caffeinated fizzy drinks and chocolate, for example, in the latter part of the day.27
- Try Green Tea: Instead try Green Tea. Although Green Tea does contain a trace of caffeine it’s known for aiding a good night’s sleep. Green Tea contains theanine, an amino acid which helps us to sleep well.28
- Eat Right: Avoid eating big meals late in the day and cut out alcohol at night because both can bring on heartburn and sit heavy inside, making it hard to fall asleep. Instead try a salad with kale and spinach which are rich in calcium which helps the brain use tryptophan, an amino acid responsible for causing us to feel drowsy.29 Generally watching what we eat in the evenings can help us to get a better night’s sleep. Sugary, highly processed foods will keep us awake.30
Instead, if you’re peckish, opt for a yoghurt as an evening snack, or a glass of milk. Milk contains tryptophan and is high in calcium; both help promote sleep.
Better still, how about a banana to go with your yoghurt and milk? Banana contains vitamin B6 and magnesium, an essential mineral, both of which can help promote better sleep. Bananas are packed with potassium, which helps our muscles to relax. Bananas also contain tryptophan, which is converted by the body into melatonin, which helps us to feel sleepy. On top of this bananas are a carbohydrate which can help make us feel drowsy too.
Try cherries, which are also a natural source of melatonin. “Eaten regularly, cherries can even help restore your natural sleep cycle and regulate your body’s circadian rhythms.”31
Salmon and halibut, for example, are high in vitamin B6, which the body needs to produce melatonin, so these fish can have a sleepy effect.
Lettuce can also help us to get a better night’s sleep because it contains lactucin which has a sedative effect on the nervous system.
Like milk, hummus contains L-tryptophan, so can be a good evening snack if we’re feeling hungry.32
Five Interesting Sleep facts
Did you know…..?
- The official record documented for the longest anyone has gone without sleep is 11 days and 24 minutes. Loss of concentration, hallucinations, disrupted vision, paranoia, mood swings, difficulty speaking and loss of memory were experienced.33
- Unusual noise, and noise during the first and last two hours of sleep, has the most disruptive impact on the sleep cycle. Noise disruption can have a negative impact on various immune system processes as well as other biological, endocrine and metabolic functions that require a regular, healthy and uninterrupted circadian rhythm to operate optimally.34
- Humans get approximately three hours less sleep a night compared to our primate cousins, chimps, baboons, rhesus monkeys and squirrel monkeys who tend to get 10 hours compared to our average of between 7.5 and 9 hours per night.35
- Sleep deprivation adversely affects our tolerance of alcohol. After just five nights of missing out on ‘enough’ sleep, the effect of alcohol on our body is doubled compared to when we are well rested and in a regular sleeping pattern.36
- Lack of sleep adversely affects bees too. Research indicates that sleep may function to consolidate memories in honeybees. “Learning is reinforced during deep-sleep, just like we would expect in humans” Bees have a similar circadian rhythm/sleeping pattern to humans and when sleep deprived are unable to remember usual daily tasks and actions, such as how to perform the waggle dance properly; the honeybee’s method of communicating where the best nectar can be found. Sleep deprived bees were also noted to have got lost returning to the hive, struggling to recall the familiar journey home.37
Supplements: 5-HTP and sleep
5-HTP is a vital naturally occurring compound in the body and is the most important active ingredient of the Griffonia Simplicifolia plant. Griffonia Simplicifolia is a vine plant that best grows on mountain slopes and termite hills of Central and West Africa. It’s been employed in this part of the world for centuries as a traditional herbal medicine, esteemed for its therapeutic and healing properties for a range of diseases. 5-HTP converts directly into serotonin and melatonin in the human brain. These are neurotransmitters which are believed to help mood, brain activity, appetite, concentration, and regulate sleep patterns. 5-HTP is thought to help aid insomnia; The conversion of 5-HTP into serotonin and melatonin in the brain can help promote a healthy sleep pattern. Melatonin has been cited as the hormone that helps regulate our wake-sleep cycle. Try coupling this with Green tea tablets, a great source of theanine which can help improve sleep; and these two supplements could help us to get some shut eye.38
Sleep for survival
Quite simply we need sleep. Sleep is essential to our survival. It’s clear that while we sleep a whole multitude of mental, physical, emotional and biological processes are taking place whichise paramount to human health. Ensuring we are getting an adequate amount of sleep each night and developing a regular sleeping pattern is intrinsically linked to overall health, well-being and vitality.
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2 Thomas Dekker (The Gull’s Hornbook, 1609) Retrieved from: http://reflectd.co/2014/02/28/the-beauty-of-sleep-quote/
7 A sleep to remember: The effects of sleep on memory: http://journals.ed.ac.uk/resmedica/article/viewFile/179/793
11 Overnight Therapy? The Role of Sleep in Emotional Brain Processing: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2890316/