We spend one-third (1) of our lives sleeping or attempting to sleep! This may seem like a lot of time spent doing nothing, but quality sleep is incredibly important to our health and longevity.
Understanding the importance of our sleep and its health effects, along with evidence-based ways to improve our sleep quality, can go a long way in improving the quality of our lives.
The stages of sleep
There are five stages of sleep – Stage 1, stage 2, stage 3, stage 4 and the REM stage (2).
This is the transitional phase between wakefulness and sleep. During this stage, your mind slowly starts to drift off and you float in and out of consciousness.
This stage occurs when you fall asleep and become unaware of your surroundings. Your body’s internal temperature decreases and heart rate slows down, as your breathing falls into a natural rhythm.
Stages 3 and 4
Stages 3 and 4 are what we refer to as ‘deep sleep’. In stage 3, your brain waves and breathing slow down. Blood pressure decreases and muscles completely relax.
These are the restorative stages of sleep, where blood-flow to your muscles increases, growth hormones are released, and tissues repair themselves. People who tend to wake up during stages 3 and 4 will find themselves disoriented for a few minutes and wanting to hit the snooze alarm!
REM sleep gets its name from the Rapid Eye Movement that occurs during this stage. The REM stage typically occurs every 90 minutes after you fall asleep, for between 10 to 25 minutes, with the duration increasing after each subsequent bout of sleep.
During this REM stage of sleep, your eyes move around, your brain is active, and your body is relaxed. This is when dreams occur. This type of sleep energises your body and brain, and helps you feel alert and focused during the day.
A typical night of sleep involves moving through these 5 stages in cycles, going from stage 1 through 4, into REM sleep and back to stage 1.
Why is sleep so important?
Sleep regulates our “internal clock”, known as the ‘circadian rhythm,’ which modulates almost everything – from the time you feel tired, to your cognitive functioning, metabolism and overall health (5, 6, 7).
The circadian rhythm is associated with up to 80% of genes in mammals (8), as a result of which sleep plays a direct role in a number of systems and processes, including:
Sleep modulates your physical activity, appetite, body temperature, heart rate, muscle tone, and hormone secretion (9). A number of studies have associated sleep deprivation with a higher prevalence of obesity.
Chronic sleep deprivation may cause weight gain by affecting the way the body processes and stores carbohydrates, and by altering the levels of the hormones that affect our appetite (leptin and ghrelin) (10). Inadequate sleep is also believed to decrease protein-building, potentially increasing protein breakdown, favouring the loss of muscle mass (5). This hinders muscle-recovery and growth after exercise.
Sleep issues have also been linked to increased inflammation, hormonal imbalances like polycystic ovarian syndrome (PCOS) (11), inflammation, and an increased risk of type-2 diabetes, heart disease and stroke (5).
A good night’s sleep is commonly recommended as ‘the best medicine’, and for good reason. Sleeping affects various immune parameters- it’s associated with a reduced risk of infections, and can even improve outcomes of infections and the body’s response to vaccinations (by affecting our adaptive immune system). In fact, prolonged sleep deficiency can compromise immunity and overall health. (12, 13, 14)
Growth, development and repair
When you’re asleep, your body replenishes and repairs itself. It needs this time to repair muscles and release the hormones that maintain growth.
Sleep plays a vital role in the growth and development of children. Levels of our growth hormone are typically elevated at the onset of sleep, with its levels peaking during stages 3 and 4 (deep sleep).
Memory and learning
Sleep has been shown to facilitate critical changes in the brain that enable learning and memory. It essentially helps consolidate recently acquired information for long-term storage. Research has shown that while we sleep, our brain cells communicate with each other, to incorporate everyday changes and circumstances into our memory (16, 17, 18, 19).
Waste-disposal from the brain
In most regions of the body, a network of intricate fluid-carrying vessels, known as the lymphatic system, eliminates protein waste and damaged cells from our tissues (20).
The brain lacks lymphatic drainage; it’s able to get rid of its waste through specialised brain cells, and this largely occurs when we sleep (21). Sleep deprivation can slow down this process, leading to a build-up of waste in the brain (22).
How much sleep do we need?
Sleeping in one block for 7 – 9 hours is believed to be the result of industrialisation, rather than driven by our biology. Historically, humans are believed to have slept in two or more blocks of 3-4 hours, just like other mammals (23). However, given that most of us (and our professions) are more tuned to a single sleep phase (‘monophasic’), a good night’s sleep would be defined as 5-6 full sleep cycles, from stage 1 through REM sleep (24, 25). However, it is important to note that individual sleep requirements vary, based on factors such as age, lifestyle, activity levels and stress, with some individuals requiring far less sleep than others (26).
1] Falling asleep within 15-20 minutes of lying down to sleep.
2] Regularly sleeping a total of seven to nine hours in a 24-hour period.
3] Sleeping continuously — not lying awake when you wish to be sleeping.
4] Waking up refreshed.
While there may be some variations (due to isolated events like a stressful day or that late-night cup of coffee), most (if not all) of these four guidelines should apply. If not, we’d recommend consulting a healthcare professional, to address any underlying issues or lifestyle changes that could improve the quality of your sleep – especially given the vital role it plays in ensuring good health!
How to get better and more sleep
A few simple tips can help you optimise the quality and quantity of your daily sleep:
Turn off the lights and keep away electronic devices before bedtime.
Light suppresses melatonin production and disrupts the sleep cycle, which is why it’s easier to sleep in a dark space (29). Blue light from mobile screens, LED TVs etc. disrupts melatonin production, tricking your brain into feeling that it’s daytime (30).
Avoid looking at bright screens two to three hours before it’s time to go to bed. If you work a night shift or use a lot of electronic devices at night, consider wearing blue-blocking glasses or installing an app that filters the blue/green wavelength at night on your devices. Expose yourself to lots of bright light during the day, which will boost your ability to sleep at night, as well as your mood and alertness during daylight (31).
Prioritise your sleep, and keep the pattern consistent
Neglecting sleep through the week and trying to catch up on the weekends doesn’t work (32). Our bodies quickly adapt to our habits, for better or worse, and sleeping for short periods of time followed by two days of excess sleep is recognised as a constant disturbance in the cycle. In fact, research has shown that sleeping in on the weekend actually makes you more tired in the following week (33). Setting a routine to sleep at about the same time, and for the same duration every night, is ideal.
Stay active during the day
Studies have shown that being inactive is associated with poorer sleep, and, conversely, getting exercise during the day may help you sleep better at night.
Get comfortable at night
Adopt a relaxing routine before bed, like listening to calming music (36) or taking a warm bath (37). Sleeping in a quiet, dark room at a comfortable temperature (between 16°C to 19°C, approximately) can help you sleep better. Too much activity before bed, feeling too warm or being in a noisy environment are all linked to poor sleep (38).
Minimise caffeine, alcohol and nicotine
Don’t drink too much fluid at night
Limiting fluid consumption at night will lessen your need for bathroom trips, which may disrupt your sleep (43).
If you’re feeling tired during the day, take a nap
A nap of less than 30 minutes during the day promotes wakefulness and enhances our performance and learning ability (44, 45). Short naps do not affect our night sleep unless they’re very close to bedtime (46).
Get plenty of vitamins B12, B6, and D3, magnesium and tryptophan
Nutrition plays a role in all aspects of our health, including sleep.
Deficiencies in vitamin B12, B6 and magnesium have been linked to trouble sleeping (47, 48, 49), while vitamin D3 has been shown to improve our quality of sleep (50). Proteins rich in the amino acid ‘tryptophan’, a precursor to melatonin, have been shown to promote sleepiness (51). Tryptophan is commonly found in oats, bananas, dried prunes, milk, tuna fish, cheese, bread, chicken, turkey, peanuts, and chocolate.
The health benefits of good sleep have been studied extensively, and it’s scientifically proven that a good sleep cycle is great for our overall health (both physical and mental).
We hope this blog was informative! Feel free to ask any questions or share your thoughts as a comment below.