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[Article revised on 11 April 2020.]
Sleep is the best meditation. —Dalai Lama
We spend about a third of our lives in sleep. But why do we sleep, and how can we do it better?
Sleep is critical to our cognitive performance and mental and physical health. Studies have found that sleep-deprived employees are less satisfied, less productive, and less creative. They are also more disinhibited, and more likely to engage in dishonest and unethical behaviour.
Cabin crew on long-haul flights suffer from frequent jet lag, which has been associated with cognitive deficits such as increased reaction times and impaired working memory. And despite being leaner and healthier than average, they are at a higher long-term risk of physical health problems such as cancer and diabetes.
According to the American Academy of Sleep Medicine (AASM), there are over 250,000 sleep-related motor vehicle accidents each year, and sleep-related accidents account for one in every five serious motor vehicle injuries. Most striking of all, people who drive after 17 to 19 hours of wakefulness actually do worse than people who are above the drink-drive limit.
Contrary to received wisdom, chronic sleep deprivation (a lack of sleep that builds up over time) is even more dangerous than total sleep deprivation (not sleeping at all). One study looking at cognitive deficits found that the long-term restriction of sleeping time to six hours or fewer could compare to up to two nights of total sleep deprivation. And unlike people with total sleep deprivation, people with chronic sleep deprivation are largely unaware of their cognitive deficits and, therefore, more likely to endanger themselves and others.
Fatal insomnia, a rare prion disease of the brain, leads to confusion, delirium, and death within an average of just 18 months.
Adequate sleep, on the other hand, greatly improves learning and memory. During sleep, the brain sorts out memories, consolidating useful or unusual ones and discarding unhelpful or ‘duplicate’ ones. Sleep also supports procedural memory, which is the memory of how to do things, like chopping vegetables or riding a bicycle. Olympic athletes have come to recognize that sleep is just as important as diet and training, and aim to sleep at least eight hours a night, with many also making time for strategic daytime naps.
As well as memory, sleep enhances mood and cognitive function—one reason why we ‘sleep on it’ and ‘sleep it off’. Experimental subjects who had their sleeping time restricted to four to five hours a night over one week reported feeling more stressed, angry, sad, and mentally exhausted. After returning to their normal schedule, they experienced a dramatic improvement in mood. In people with a mental disorder such as depression or bipolar disorder, adequate sleep often suffices to prevent or forestall a relapse, and also plays a critical role in recovery.
In terms of physical health, the benefits of adequate sleep include fewer food cravings, greater weight loss, fewer viral infections, lower risk of cardiovascular accidents (strokes and heart attacks), lower risk of dementia, and longer life expectancy. The cherry on the cake is that sleep also makes us look younger and more attractive, the so-called ‘beauty sleep’. To save on sleep is clearly a false economy.
Over the years, I think I’ve come to understand the secret to refreshing sleep. During sleep, the brain cycles through four successive stages, the last of which is REM or ‘rapid eye movement’ sleep. Each four-stage cycle takes an average of about 90 minutes, with much more time spent in REM sleep towards the end of the night and just before natural awakening.
Waking up after REM sleep is associated with feeling refreshed, and experimental subjects who were woken up after REM sleep performed better on tasks like anagrams and creative problem solving. In contrast, being woken up from deep non-REM sleep can leave us feeling groggy and grouchy—as though we had woken up ‘on the wrong foot’ or ‘on the wrong side of the bed’.
Sleep Essential Reads
REM sleep, as you know, is also associated with dreaming, which serves critical functions such as assimilating experiences, processing emotions, and generating and testing ideas. In fact, the brain can be more active during REM sleep than during wakefulness. Many great works of art have been inspired by dreams, including several of Edgar Allan Poe’s poems and short stories, Salvador Dali’s Persistence of Memory, and Paul McCartney’s Let It Be.
The importance of REM sleep and dreaming to psychic health is not to be underestimated. But because it is stacked towards the end of the night, a lot of this precious REM sleep can be lost by sleeping short or waking up to an alarm clock or phone call—leaving us tired, confused, and irritable.
So, in a sentence, the secret to refreshing sleep is to wake up naturally after a sustained period of REM sleep. There is much wisdom in the old saying that ‘one hour’s sleep before midnight is worth two after’—meaning, go to bed early!
Sleep is important on so many levels. Yet insomnia—difficulty falling or staying asleep—afflicts as many as one in three people, and almost everyone could do with better, more restorative sleep. The most important causes of short-term insomnia, which is the commonest type of insomnia, are: a stressful life event, a poor sleeping environment, and an irregular routine. Other common contributors to insomnia include poor sleeping habits, psychological disturbances such as anxiety and depression, physical problems such as pain and shortness of breath, certain prescription drugs, and alcohol and drug misuse.
Taking all these factors and more into account, here are my ten steps to happy sleep.
1. Set up a fairly strict routine. Allocate a time for sleeping (for example, 11pm to 7am) and don’t use that time for anything else. Avoid daytime naps or make them short and regular. If you have a bad night, avoid sleeping late, as this makes it more difficult to fall asleep the following night.
2. Wind down before bedtime. Devise a relaxing bedtime routine. This may involve breathing exercises or meditation, or simply reading a book or listening to some gentle music. A hot bath can be helpful: By diverting blood to the periphery, it leads, once out of the bath, to a fall in core body temperature, which in turn invites sleep. On the other hand, bright lights and bright screens can play havoc with your body clock, so avoid TV, computers, and phones around bedtime.
3. Eat a wholesome evening meal that contains a good balance of protein and complex carbohydrates. Eating too much can make it difficult to fall asleep; eating too little can disturb our sleep and decrease its quality. And don’t leave it too late: dining late or eating just before bedtime can lead to indigestion or heartburn during the night.
4. Enjoy a hot, non-caffeinated drink before going to sleep. Good candidates include herbal tea, malted milk, and hot chocolate. But remember that sugar is a stimulant, so keep it to a minimum. In time, your hot drink could serve as a sleeping cue.
5. Avoid caffeine and alcohol, particularly in the evenings. Levels of adenosine in the brain rise with prolonged wakefulness, leading to sleepiness. Caffeine blocks adenosine receptors, which makes it harder to fall asleep and decreases the overall length and quality of sleep. Alcohol may make it easier to doze off, but, like caffeine, decreases the overall length and quality of sleep, and especially of restorative REM sleep.
6. Optimise your sleeping environment. Sleep in a familiar, dark, and quiet room that is adequately ventilated and neither too hot nor too cold. If possible, use this room for sleeping only, so that you come to associate it with sleep. In time, the room itself could serve as another sleeping cue. If necessary, wear a sleep mask and ear plugs. And switch off your phone. Small things can make a big difference: I find cool linen sheets very helpful at the height of summer, whereas in the depth of winter I like to have a thick, soft, cosy blanket on top of my regular bedclothes.
7. Don’t get wound up. If sleep doesn’t come, don’t get anxious or annoyed and try to force yourself to sleep. The more aggravated you become, the less likely you are to fall asleep. Instead of tossing and turning, get out of bed and do something relaxing and enjoyable for half an hour before giving it another go.
I used to have a lot of trouble falling asleep. But now I can fall asleep almost on demand, and I sleep very deeply. The key I think is to clear your mind and relax. You can try deep breathing, or do what I do, which is to make myself feel grateful for the things we tend to take for granted, like being able to walk, or being safe and warm in our bed. I discuss this technique in more detail in my new book: The Secret to Everything: How to Live More and Suffer Less.
8. Shake your booty. Exercise (even just going for a walk) reduces arousal and anxiety and also helps with other aspects of psychological and physical health. In respect to psychological health, it decreases stress, improves concentration and memory, boosts self-esteem, and directly lifts mood through the release of natural antidepressants called endorphins. In respect to physical health, it slims down and tones the body, decreases blood pressure and heart rate, increases physical strength and endurance, and improves posture and flexibility. Physical activity is helpful in tiring us out, but it is also a short-term stimulant, so avoid exercising close to bedtime.
9. Reduce your overall stress. Things that you can do to reduce stress include: going for a nature walk, giving and receiving massage, having a hot bath, laughing, singing, dancing, burning incense, and enjoying a delicious meal. Each of these activities should also give your endorphins a good boost. Beyond pleasure and relaxation, try to do something fulfilling each and every day, like working towards a long-term goal or helping someone. As Leonardo da Vinci said, a well-spent day brings happy sleep—and I would add, a well-spent life brings happy death.
10. If insomnia persists, speak to your doctor. In some cases, insomnia has a very specific cause, such as a physical problem or an adverse effect of medication, that requires your doctor’s attention. While sleeping tablets may seem like a solution, they are best avoided in the longer term because of their adverse effects and high potential for tolerance (needing more and more to produce the same effects) and dependence—not to mention that the quality of drug-induced sleep may not be as high as that of natural, non-assisted sleep. Psychological alternatives to sleeping tablets that you can discuss with your doctor include cognitive behavioural therapy (CBT) and sleep restriction therapy.
Don't make the common, almost universal mistake of underestimating sleep. Time spent in sleep is time well spent, especially that extra hour or two of REM-rich sleep.
Good night.
LinkedIn Image: Dmytro Zinkevych/Shutterstock
References
Christian MS & Ellis AP (2011): Examining the effects of sleep deprivation on workplace deviance: A self-regulatory perspective. Academy of Management Journal 54 (5): 913-934.
Naska A et al (2007): Siesta in healthy adults and coronary mortality in the general population. Arch Intern Med 167 (3): 296-301.
American Academy of Sleep Medicine (2009). Drowsy Driving Fact Sheet (PDF).
Williamson AM & Feyer AM (2000): Moderate sleep deprivation produces impairments in cognitive and motor performance equivalent to legally prescribed levels of alcohol intoxication. Occup. Environ. Med. 57 (10): 649–55.
Drummond SPA et al. (2006): Effects of two nights sleep deprivation and two nights recovery sleep on response inhibition. Journal of Sleep Research 15 (3): 261–5.
Van Dongen HP et al (2003): The cumulative cost of additional wakefulness: dose-response effects on neurobehavioral functions and sleep physiology from chronic sleep restriction and total sleep deprivation. Sleep 26 (2): 117-26.
Rasch B & Born J (2013): About Sleep's Role in Memory. Physiol Rev. 93 (2): 681–766.
Dinges D. et al. (1997): Cumulative Sleepiness, Mood Disturbance, and Psychomotor Vigilance Decrements During a Week of Sleep Restricted to 4 – 5 Hours Per Night. Sleep 20 (4): 267–277.
