On average we sleep for one-third of our lives. Nowadays we understand its cyclical pattern and its essential roles for our physical and mental equilibrium. Since the 1960s our lifestyles have reduced the time we sleep on average by an hour-and-half and, according to the INVS, the French national sleep research institute, 40% of the French have sleep problems and 22% suffer from insomnia*, while 30% of 15-19 year olds have a significant sleep deficit**. A few factors to help understand this fundamental requirement in order to retrain and, where necessary, change your behaviour in order to sleep well... whatever your age.
* Opinionway survey carried out for the INVS and the MGEN mutual insurance company with 1,010 people in France aged 18 to 65, with summary by INVS published on 15 March 2012:http://www.santepubliquefrance.fr
Not one, but several types of sleep... and different sleepers as well
That ship has sailed: this popular expression used when we are unable to fall asleep, clearly indicates that we are aware that sleep consists of a succession of phases.
Indeed, throughout the night, 4 to 6 sleep cycles lasting approximately 90 minutes occur, in the same order, broken down into light slow wave, then deep slow wave sleep, followed by recovery and regeneration phases and REM (rapid eye movement) sleep, during which emotions and memorization are managed. These same stages, with their own specific roles, occur throughout life, though their pattern changes. For example, as we age, sleep becomes fragmented, with night losses compensated for by naps. The duration of light sleep lengthens at the cost of deep sleep.
Sleep also differs in its duration. The average physiological duration of sleep is estimated to be 18 hours at birth, 12 hours at 3 years, 10 hours at 10 years, 9.5 hours between 13 and 19 years and 7.5 hours for adults. However, genetic variability exists from the very earliest age, which confirms the notion of an individual sleep requirement.
What happens during sleep?
Essential sleep hormone
Produced by a small gland at the base of the brain, this molecule is synthesized during the night, with a peak around 3 am. Synthesis then stops with daybreak. Night-time melatonin levels are thus 10 times higher than daytime levels. Secreted into the blood, it is conveyed to the organs and can pass through the membranes of every cell in the body. Melatonin determines the daily and seasonal rhythms of our body's major biological functions. Thus, as darkness falls, it sets our internal clock to the sleep position and, as day breaks, it sets it to the wake position. Melatonin secretion and/or effectiveness can be disrupted by many factors, leading to sleep disorders. The main factors are as follows:
Natural or artificial light, -with blue light inducing the greatest inhibition-. The brighter the light, the greater the effect.
Electromagnetic waves generated by electrical devices, mobile phones, relay antennas, radios,… an invisible pollution affecting melatonin production.
Age, with the progressive attenuation of secretion.
Certain medicines. Talk to your doctor, pharmacist or therapist.
Do you have a sleep deficit? Poor quality sleep?
What are the long- and short-term consequences?
While the average adult daily sleep requirement is 7 to 8 hours, many people sleep less than 6 hours per night. What are the short- and long-term health consequences?
The secrets of a good sleep
Some daily recommendations
During the day or in the afternoon
In the evening
• Spend some time outside between 10 am and 2 pm.
• Look out for signs of sleepiness (yawning, stinging eyes, etc.), and pay heed to them...
• Avoid drinking alcohol and high-caffeine drinks, which reduce melatonin production.
• Ideal room temperature: 18 to 20°C. Avoid intensive sports in the evening, they increase body temperature and keep you awake.
• Play sport, get some air.
• Turn down the lights. Eliminate all causes of sleep disruption: noise, light (television, screens, etc.), tobacco, tea, coffee... Plunge the bedroom into darkness.
• Carry out a routine in order to synchronise the internal clock with regular hours of going to bed and getting up: also favour taking a nap over sleeping in.
• Favour calming activities such as reading and soft music.
• Put stressful matters out of your mind.
• Maintain your own bedtime and getting up routine.
• Bedtime routines are a good thing: book, bath, removing make-up…
Sleep is also a function of what you eat
What you eat and when you eat it can impact sleep. It is essential to eat three meals per day with an appropriate composition; some foods tend to induce sleep, while others act as a stimulant.
Eat your evening meal at least one and a half hours before going to bed (digestion increases body temperature, disrupting sleep). Restrict fats which slow down digestion and cause fragmented sleep.
Tryptophan and complex sugars: a sleep aid
The day-night rhythm is regulated by melatonin which is itself synthesised from serotonin. This sleep hormone is vital for getting off to sleep. The production of serotonin depends on the blood concentration of tryptophan, an amino-acid.
Eat these foods in the evening and make sure you eat them along with dishes containing lentils, quinoa or rice… to help tryptophan to “get into” the brain. Foods with the highest levels of tryptophan: chick peas, parsley, parmesan, wholegrain rice, gourd seeds, soya, cod, dairy products, walnuts, eggs, pulses, bananas…
These foods should be accompanied by dishes based on lentils, quinoa, rice, etc. to help the tryptophan enter the brain.
Wurtman RJ, Wurtman JJ, et al. Effects of normal meals rich in carbohydrates or proteins on plasma tryptophan and tyrosine ratios. Am J Clin Nutr. 2003 Jan;77(1):128-32. Minet-Ringuet J, Le Ruyet PM, et al. A tryptophan-rich protein diet efficiently restores sleep after food deprivation in the rat. Behav Brain Res. 2004 Jul 9;152(2):335-40.
Plants, minerals and vitamins help you to fall asleep and to enjoy a calm and refreshing sleep.
Hawthorn and lemon balm: their relaxing effects are traditionally used to reduce tension, agitation and irritability in anxious subjects whose sleep is disturbed by thoughts going round in the head.
Hoarhound:reduces nervousness in children and adults, notably those with minor sleeping difficulties.
Passion flower: promotes night time rest and relaxation. It provides precious support during periods of mental and nervous stress.
Eschscholtzia: promotes relaxation, acts as a morale booster. It also promotes natural sleep quality.
Magnesium, zinc and iron: these are actively involved in the conversion of tryptophan into serotonin.
Vitamins B3 and B6 are also required for the conversion of tryptophan into serotonin.
Vitamins B6, B9 and B12 are indispensable alongside an amino-acid, methionin, for converting serotonin into melatonin.
Many studies have shown that taking melatonin is beneficial in cases of sleeping disorders or jet-lag. Thus, melatonin helps reduce the time required to fall asleep (the beneficial effect is achieved by taking 1 mg of melatonin) and attenuates the effects of jet-lag (the beneficial effect is achieved by taking at least 0.5 mg just before going to bed on the first day of the trip and for a few days following arrival at your destination).
For futher information
Le sommeil, le rêve et l’enfant Docteur Marie-Josèphe Challamel, Docteur Marie Thirion Publisher: Albin Michel April 2011
Mieux dormir et vaincre l’insomnie Docteur Joëlle Adrien Publisher: Larousse May 2014