Sleep plays a crucial role in our physical and mental health, and therefore in our long-term quality of life. Far beyond a simple rest period, it’s essential for cell regeneration, memory, and much more. Because sleep concerns us all, here’s a look at 10 essential questions.
(1) WHAT HAPPENS DURING A NIGHT OF SLEEP?
A night of sleep is divided into stages and cycles. The cycle is a sequence of stages from light sleep to deep sleep, then to dream sleep. There are four stages of sleep in total. Stage 1 is when we first fall asleep, and it lasts only a few seconds or minutes. This sleep is very light. Stage 2 is still light sleep, but tends to be slightly deeper, and can sometimes be experienced as light dreaming. This is an important stage for energy recovery and memory consolidation. At stage 3, we enter deep sleep, and it becomes difficult to wake the sleeping person. The fourth and final stage is paradoxical sleep. This is known as REM sleep, or rapid eye movement sleep. The sleeper’s eyes will move under the eyelids, a sign of intense dream activity. It is also during this stage that people have vivid and even “bizarre” dreams. The onset of REM sleep ends the sleep cycle, which in adults will have lasted between 80 and 120 minutes. We may return to wakefulness at the end of a sleep cycle, which is perfectly normal for a sleeper. Another sleep cycle begins, and so on until the end of the night.
(2) HOW MANY HOURS OF SLEEP SHOULD WE GET EACH NIGHT?
The famous magic number of 8 hours’ sleep that we often hear about stems from population studies that showed that, on average, a night between 7 and 9 hours was sufficient for people in good health. The most important thing is to find your own number, because sleep is an individual need. Our need for sleep is measured by the quantity (and quality) of sleep we get, which enables us to function during the day, carry out our daily tasks and maintain a good level of energy. However, recent research suggests that the consistency of our bedtimes and wake-up times is the key to good health, as much as, if not more than, the number of hours we sleep.
(3) IS IT POSSIBLE TO BE SLEEP-DEPRIVED?
Yes, and unfortunately, the vast majority of the population suffers from sleep deprivation, i.e., we don’t get enough sleep in relation to our sleep requirements. For example, a person may voluntarily cut back on sleep during the week for a variety of reasons, including productivity and performance, and then try to make up for the hours of sleep missed by spending more time in bed during the weekend. This upsets the biological clock and should be avoided if you suffer from insomnia. Otherwise, it’s a good idea to bear in mind that when you have a short night’s sleep or a less recuperative night’s sleep, a natural rebalancing takes place the following night. This is because the brain, according to the principle of homeostasis, will naturally seek deeper sleep to recover, without having to make up for every hour of lost sleep.
(4) HOW DO YOU SWITCH OFF YOUR BRAIN BEFORE GOING TO SLEEP?
Stress and anxiety are the worst enemies of sleep. Cortisol, the stress hormone, influences the physiological processes that regulate sleep. We therefore want to reduce cortisol levels before bedtime, just like our body temperature, which is why we should avoid intense physical activity late in the evening. Intrusive thoughts and ruminations also keep us awake and contribute to increased stress in the evening or at night. Taking breaks to relax and unwind during the day will help to train the brain, which likes to go a hundred miles an hour, to relax, and will make it easier to relax in the evening.
(5) WHAT SHOULD YOU DO IF YOU SUFFER FROM INSOMNIA?
You shouldn’t stay in bed when you can’t fall asleep. This habit, especially if you are prone to insomnia, helps to maintain it over time. If you can’t fall asleep after 20 minutes, get out of bed and go to another room. This will avoid creating a cognitive association between being awake and being in bed. It is recommended to do a relaxing, even boring activity, with no secondary gain (don’t do your taxes, for example). Read about a subject that doesn’t interest you, such as an instruction manual. Above all, you must avoid your cellphone and television, which stimulate the mind. The idea is not to reward the brain for being awake at night. The goal is to create a sleep-bed association, meaning that “when I’m in bed, I sleep.”
(6) IS IT A GOOD IDEA TO TAKE A NAP?
It may be appropriate if you feel the need, and if you do not suffer from sleep problems such as insomnia. A “power nap” lasting 15 to 20 minutes is recommended to get some light sleep only. It’s also important not to nap too late in the day, so that you can build up the “sleep requirement” throughout the course of the day, allowing you to fall asleep at night.
(7) WHY DON’T SOME PEOPLE DREAM?
In principle, everyone dreams, even those who think otherwise. If we don’t wake up during REM sleep, we won’t remember our dreams. There isn’t enough room in our memory to store them all, unless we make an active effort to remember and write them down.
(8) IS IT TRUE THAT SLEEP CHANGES WITH AGE?
Sleep changes throughout life, from birth to old age! As soon as we reach our forties, we notice a gradual weakening of sleep, which continues with age. Sleep grows lighter, and nocturnal waking becomes more frequent. In men, the decrease in deep sleep tends to be more noticeable, and may be linked to testosterone, according to research. In old age, the biological clock moves forward: we go to bed earlier, and get up earlier.
(9) ARE SLEEP TRACKING APPS AND SMARTWATCHES REALLY USEFUL?
We must be cautious in our interpretations, since this type of application does not offer precise measurements. They rely mainly on body movements and heart rate. Only electrodes placed on the body (as in polysomnography) provide reliable data on sleep stages. These applications therefore offer approximate data that could undermine our confidence in our sleep and our subjective impression of having slept well. Unless you use them to remind yourself that it’s time to go to bed, you’re better off without them!
(10) DOES THE EARLY BIRD REALLY CATCH THE WORM?
It’s probably a saying popularized by the early risers among us, but it’s not necessarily true! Are you more of a night owl and a late riser, or more of an early sleeper and an early riser? Or somewhere in between? This is called a chronotype, and it’s partly genetically determined. It’s important to be in tune, as far as possible, with your chronotype.
READING SUGGESTIONS TO LEARN MORE
- Relief from Insomnia: Getting the Sleep of Your Dreams by Charles M. Morin (2nd ed.)
- Sleep and You: Sleep Better, Live Better by Diane B. Boivin
