Sleep - The latest evidence
6 Benefits of Sleep
Why do we sleep, and what happens when we don't get enough sleep
Sleep is an essential aspect of maintaining good health and well-being. However, it is not always easy to get enough sleep due to various reasons such as family demands, shift work, relationship issues, or chronic exposure to stress. This often leads to complaints about feeling tired all the time.
Although it may be tempting to ignore the negative effects, research indicates that not getting enough sleep is something to be taken seriously.
It is often recommended that we should spend one-third of our time sleeping[1], that is depending on our individual needs. Sleep is essential for good health and well-being. During sleep, our body actively heals and repairs tissues and detoxifies unwanted toxins and byproducts of metabolism, and also no longer needed hormones. Lack of sleep can lead to a range of health problems, including obesity, diabetes, cardiovascular disease, and depression.
However, with at least 30% of the population experiencing sleep disturbance[2], a significant number of people are clearly not getting enough sleep. There are many reasons why people may not be getting enough sleep. These include stress, anxiety, medical conditions, and poor sleep habits. It is important to address these issues in order to improve sleep quality and overall health.
Research shows that adults who sleep for less than seven hours a day have a greater chance of developing chronic conditions such as obesity, diabetes, high blood pressure, heart disease, stroke, depression and mental distress.[3-5]
Experts on sleep recommend a consistent sleep schedule (even on days off or weekends) and creating a relaxing bedtime routine to help promote quality sleep. Additionally, avoiding caffeine and alcohol before bedtime, as well as limiting screen time in the evening, can also improve sleep quality.
The Benefits of Sleep: Why a Good Night's Rest is Essential for Your Health
Getting enough quality sleep is one of the most important things you can do for your health. Not only does it help you feel more alert and productive during the day, but it can also have long-term benefits for your overall well-being. Here are some reasons why:
Improved Cognitive Function and Mental Well-being: Poor sleep can lead to irritability and mood swings, partly due to the impact of stress hormones on blood sugar and hunger. This is why chronic lack of sleep is associated with many mental health conditions, such as depression, anxiety, and psychosis. Studies have shown that individuals with insomnia experience more symptoms of anxiety and depression than those without insomnia. Inadequate and/or low-quality sleep increases the risk of depression, anxiety, and other psychological issues. In fact, 90% of people diagnosed with depression report low sleep quality.[6,7]
Reduced risk of short-term issues: Poor quality sleep, or lack thereof, can have a significantly negative impact on our overall health. When feeling fatigued, it may be difficult to operate at full capacity, and your brain may find it difficult to do well all it is tasked with. Short-term issues may thus include brain fog, lowered attention span, difficulties with concentration and focus, and poor memory recall. It may also impact learning and retention of information. In some studies, a deficit of as little as 90 minutes in nocturnal sleep (for just one night) can lead to a reduction of objective daytime alertness by one-third.
Reduced Risk of Chronic Disease: In addition to short-term effects, researchers are also studying the longer-term effects of sleep deprivation. Poor quality sleep or lack of sleep has been linked to significant health problems, including obesity, diabetes, weakened immune systems, and even certain cancers.
Improved Gut Health: Taking a break from eating can be beneficial for your gut, and sleep allows the body to fully extract nutrients from the food we eat (in a totally relaxed state). Studies show that intermittent fasting or time-restricted eating may reduce inflammation and improve the health of your gut microbiome. thus, some people may benefit from extending their overnight fast, especially if they are on a particular (unsupervised) diet such as the paleo diet or a type of ketogenic diet. Additionally, a greater diversity of beneficial gut bacteria is associated with better sleep, while other types of bacteria are linked to poor sleep quality.[8] Also, it may also have a greater impact on the histamine system. Histamine dysfunction, which is often naively referred to as histamine intolerance, can lead to sleep problems since histamine is known to act as a neuroexcitatory neurotransmitter. In fact, many people struggle with falling asleep due to histamine problems.
Increased Physical Performance: Sleep is essential for recovery and muscle repair. Not only does sleep help to repair muscles, but it also helps to recharge the mind and body. Sleep is especially important for athletes and active individuals who need to perform at their best. By getting enough sleep, they may see significant improvements in their physical performance. Additionally, sleep has been shown to help reduce the risk of injury and illness, both of which can be detrimental to an athlete's ability to train and perform. So, it's safe to say that getting enough sleep is a key component to achieving optimal physical performance.
Improved Immune System: While we sleep, our body produces cytokines, antibodies, and immune cells. These molecules work together to protect us from pathogens, fight infections, and reduce inflammation. Research has shown that lack of sleep can inhibit our immune response, making us more susceptible to illnesses and infections, which is especially important to consider when we are stressed or already sick.
As you can see, there are many reasons why good quality sleep is important for your health and well-being. If you're struggling to get to sleep, get enough sleep or feel refreshed upon rising, try establishing a regular sleep schedule (even on days off or weekends), creating a relaxing bedtime routine, and avoiding caffeine and electronics before bed.
What happens when we don't get enough sleep?
Research shows that adults who consistently sleep for less than seven hours a day are at a greater risk of developing a range of chronic conditions.[3] These conditions include obesity[4], diabetes, high blood pressure, heart disease, stroke and mental distress.[5]
It is important to note that these are not just minor health concerns, but rather significant and potentially life-altering conditions. Therefore, it is crucial to prioritise getting enough sleep to reduce the risk of developing long-term chronic issues and being medicated as a result (e.g., polypharmacy).
“The main short-term issue with lack of sleep that I come across is its mental impact. This includes tiredness at work, reduced work output, memory and concentration decreases.
“Another short-term problem with decreased sleep is reduced immune function. This leads to susceptibility to illness, especially in the winter”
Dave Gibson, co-author of The Art of Falling Asleep, explains further that the perfect number when it comes to sleep seems to be eight for most adults, with teenagers and children requiring more, and older people appearing to need less.
Because we actually sleep in cycles of around 90 minutes, seven and a half hours is the best guide if someone wants to get specific. For people who require more sleep, nine hours of sleep would be their best number.
Although, finding the sweet spot is harder for some people. Some individuals are able to function without sleepiness or drowsiness after as little as six hours of sleep, while others can’t perform at peak unless they’ve slept for 10 hours.[6]
How technology disrupts sleep
A study conducted in Norway examined the relationship between the use of electronic devices among adolescents and their sleep patterns. It found a negative association between device exposure and sleep duration, suggesting that technology use can negatively impact sleep.[Norway Study]
Here is another important quote from Gibson: “In the evening, modern teenagers now face a host of challenges. Balancing ever-increasing amounts of homework, real life and online social demands, which is all on top of their natural changing body clock. These challenges encourage teenagers to go to bed later.
“The natural shift in a teen’s circadian rhythms, ‘sleep phase delay’, delays their need to sleep for about two hours. Before puberty, the body becomes naturally sleepy around 8:00pm or 9:00pm. As puberty begins this rhythm shifts a couple of hours later, and we tend to want to go to sleep around 10:00pm or 11:00pm. This change is often a hard adjustment for a teenager; consequently, the image of a parent struggling to wake their teenager in time for school has become a familiar representation of modern day family life.”
The advice is, therefore, to commit to regular exercise during the day (not too close to bedtime) and a healthy, nourishing balanced diet. Set an electronic curfew at least one hour before bedtime, remove phones from the bedroom and establish a regular bedtime routine.
Find out how much sleep you need
To establish how much sleep your body needs, many experts suggest waking up without an alarm. First, decide when you want to wake up and count back seven and a half (or nine) hours. If you do not wake up just before the alarm, then go to bed slightly earlier each night until you can wake up without an alarm.
How to restore broken sleep
While it is possible to reverse the mental effects of sleep deficit through extra sleep over the weekend, experts warn that the long-term risks associated with a lack of sleep are not compensated for. Other experts in sleep do not recommend oversleeping on weekends (or days off), because it destabilises further your body clock. If you need 15-19 hours to feel sleepy, then every time you oversleep you delay the time by which you be able to fall asleep. This will lead you to start the week with a sleep deficit and already tired.
Here are some suggestions for you to be able to get a better night's sleep:
Caffeine intake: If you feel desperate for that cup of coffee in the morning, so you can feel as closely as possible to your best self, then cutting out on caffeine may be the answer. Excessive intake of caffeine can disturb sleep by affecting the adenosine system[7-9] and reducing the production of melatonin, the sleep hormone. The half-life of coffee can be between 6 and 8 hours. This means that after this time, half of the caffeine consumed is still circulating in the bloodstream. Further to this, new research shows that the quarter-life of caffeine is 12 hours. This means that if you drink a coffee at noon, 25% of the caffeine is still affecting your brain and, therefore, keeping you awake at midnight.[10] If you drink more coffee in the afternoon and you’re a slow metaboliser, higher concentrations of caffeine continue to keep you alert at times when you should unwind and prepare to sleep. This plays heavily on the stress response too and may keep you chronically in a state of fight-or-flight and affect your stages of sleep (you may find it difficult to reach the deep stage of sleep). Finally, it may take up to 36 hours for caffeine to completely leave your nervous system.[11] If you are addicted to caffeine, there may never be such a time when caffeine is not affecting your nervous system.
Read before you sleep: A recent study confirmed that reading before bed improves the quality of sleep. Over 40% of people in the intervention group within the study felt their sleep improved when reading a book for 15–30 min immediately before trying to go to sleep for seven nights in a row.[12]
Bedroom Hygiene: Set an electronic curfew at least one hour before bedtime. This means, reducing your exposure to blue light-emanating screens, such as mobile phones, tablets or laptops. We may even recommend that you remove phones from the bedroom, so you're not tempted to reach for the phone if you're struggling to fall asleep and disturb your sleep further by triggering the brain that it is light outside (unnatural light exposure signals the brain that it is daytime)
Establish a regular bedtime routine. Sleeping in on weekends, for example, may make you feel lethargic (due to oversleeping) and less productive on those days. It may also impact your sleep as you get ready for the new week ahead. If you require 15 or more hours to feel sleepy, then by oversleeping the time by which you would feel it is time for bed will be severely delayed. For example, if you wake up at 6:30 every morning and feel sleepy and fall asleep by 22:00, then you need 15 hours and 30 minutes from being awake to sleepy. Think of it as turning an hourglass around. You will only fall asleep once the last grain of sand has fallen. This may explain why you struggle to fall asleep on Sunday night if you have overslept all weekend.
Practice mindfulness and/or gratefulness and keep a journal to keep your emotions in check and reduce the barrages that may prevent you from sleeping asleep or damage the quality of your sleep.
DO NOT HIT THE SNOOZE BUTTON. Unless you are planning for a full sleep cycle (90 minutes), hitting the snooze button and waking again anytime after 5-9 minutes (once, twice, three times?), you will be waking up every time in the middle of a new cycle. As you try to get ready for the day ahead, you will be right in the middle of a sleep cycle and your brain will not function normally. It may take up to four hours to evade this sleep cycle. This may explain why you can fall asleep again on the bus or the train extremely easily and without noticing it. However, your productivity may also be damaged further if you didn’t sleep enough in the first place because you’ve overslept at the weekend. Now you’re wondering why your week is not starting so well and you can't find the energy you need to operate at the bare minimum and coffee has become your best friend.
References
1. The ‘Philips Index for Health and Well-being: A global perspective’ – www.philips-thecenter.org/the-philips-global-index. Last accessed on 28 February 2011
2. Asif, N. Iqbal, R. Nazir, CF. (2017). Human immune system during sleep. American Journal of Clinical and Experimental Immunology. 6(6), pp. 92-96.
3. Liu, Y. et al. (2013). Sleep duration and chronic diseases among U.S. adults age 45 years and older: evidence from the 2010 Behavioral Risk Factor Surveillance System. Sleep. 36(10), pp. 1421-1427. doi:10.5665/sleep.3028
4. Ford, ES. et al. (2014). . Sleep duration and body mass index and waist circumference among U.S. adults. Obesity (Silver Spring). 22(2), pp. 598-607. doi:10.1002/oby.20558
5. Liu, Y. et al. (2013). Association between perceived insufficient sleep, frequent mental distress, obesity and chronic diseases among US adults, 2009 behavioral risk factor surveillance system. BMC Public Health. 13, 84. doi:10.1186/1471-2458-13-84
6. Beusterien KM, Rogers AE, Walslenben J et al. Health related quality of life effects of modafinil for treatment of narcolepsy. Sleep 1999; 22(6): 757-765
— Norway Study. Hysing, M. et al. (2015). Sleep and use of electronic devices in adolescence: Results from a large population-based study. BMJ Open. 5, e006748. doi:10.1136/bmjopen-2014-006748
7. Sanchez, O. (2021). The Circadian Rhythm. Energise- 30 Days to Vitality. Nutrunity Publishing, London. pp. 153-179
8. Sanchez, O. (2021). Stress and Fatigue. Energise- 30 Days to Vitality. Nutrunity Publishing, London. pp. 181-215
9. https://www.nutrunity.com/updates/sleep-and-caffeine
10. Shilo, L. et al. (2002). The effects of coffee consumption on sleep and melatonin secretion. Sleep Med. 3(3), pp. 271–273.
11. Ganesh, J. (2019). Sleep expert Matthew Walker on the secret to a good night’s rest. The Financial Time. https://www.ft.com/content/e6ccdcac-133d-11e9-a581-4ff78404524e
12. Sleep and Reading https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8740874/
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Other Sources:
Gut health affects sleep, but you can improve yours: https://joinzoe.com/learn/gut-health-affects-sleep
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