What are the health risks of lack of sleep?

What is the link between sleep and health? 

According to data collected by Firstbeat, people in the UK get on average 7.6 hours of sleep each night.

Apart from "short sleepers" who only represent about 1 to 3% of the population, adults put themselves at risk if they sleep less than 6 hours per night. After a short night's sleep, some effects can be felt immediately, such as mood changes, troubles with attention and concentration, etc. In the medium term, irritability can set in, as well as depressive syndrome and learning difficulties. When sleep deprivation becomes chronic, there is an increased risk of obesity and diabetes.

There are two main symptoms that can indicate that an individual is suffering from sleep deprivation:

• A feeling of fatigue. A person experiences gradual worsening of their physical and intellectual performance throughout the day,
  
• Sleepiness. It corresponds to a decrease in the ability to stay awake and can lead to irrepressible episodes of sleepiness.
  

Lack of sleep is not a harmless phenomenon. Sleep allows for physical and mental recovery. When an individual is deprived of sleep repeatedly or even chronically, this has many consequences for his or her health.

What are the real health risks of lack of sleep? 

The short-term consequences of sleep deprivation are as follows:

• Sensory and perceptual alterations,
  
• Restricted visual field,
  
• Slowing down of reaction time,
  
• Difficulty concentrating and lack of attention,
  
• Fatigue and daytime sleepiness,
  
• Mood swings and irritability,
  
• Disorientation, memory problems,
  
• Increased risk of accidents at work or on the road.
  

In the longer term, lack of sleep has serious consequences for a person's health:

Lack of sleep affects the mood 

A new study, published in 2021 in NPJ Digital Medicine, highlights the fact that irregular bedtimes have a considerable impact on our mood.

Indeed, people whose wake-up time varies from day to day can find themselves in just as bad a mood as people who stayed up very late or woke up very early.

The study used data from direct measurements of sleep (using devices) and mood from more than 2,100 doctors, over the course of a year; all the participants were in the early stages of their careers, and had long days and irregular working hours.

The results of the survey showed that individuals with variable sleep schedules were more likely to have higher scores on questionnaires about depressive symptoms.

The results of this survey add to what the scientific community already knows about the correlation between sleep, daily mood and the long-term risk of depression.

Thus, getting regular sleep helps maintain a good mood and increases the feeling of well-being.

Lack of sleep affects the metabolism

Lack of sleep increases appetite by modulating the hormones that regulate it (leptin, orexin and ghrelin). Thus, the increase in calories intake, combined with fatigue and potential daytime sleepiness, will result in a decrease in energy expenditure, which in its turn may lead to weight gain.

Epidemiological data also show a correlation between the average sleep time of a given population and its BMI (body mass index).

Moreover, lack of sleep also disrupts the circadian rhythms responsible for regulating the synthesis of certain hormones such as cortisol (stress hormone) and growth hormone, both of which are involved in glucose metabolism. This phenomenon favours the appearance of glucose intolerance and long-term development of type 2 diabetes, independently of the weight gain itself.

Lack of sleep affects the immune system

According to a 4-year epidemiological study, poor sleep may increase people's vulnerability to infections, particularly those caused by fungi and parasites.

Among 9294 participants who participated in the study, those reporting poor sleep quality were more often treated with antifungal and antiparasitic drugs than others.

The results of this study support the hypothesis that sleep helps the immune system to function properly and replenish itself.

How to restore good-quality sleep?

If you are suffering from chronic sleep deprivation, it is advisable to talk to your GP or a sleep specialist in order to carry out some tests. Your sleep problems could be due to an illness such as gastro-oesophageal reflux disease, hyperthyroidism, asthma, obstructive sleep apnoea or restless legs syndrome.

Nevertheless, it is important to adopt a healthy lifestyle and this can be achieved by following a few tips:

• Avoid consuming stimulants such as tea, coffee, soft drinks, etc. 8 to 10 hours before bedtime.
  
• Eat light meals in the evening. Your meals should nevertheless contain slow sugars so that you are not woken up by hunger in the middle of the night.
  
• Do not use electronic devices such as telephones, tablets, laptops at least 2 hours before your bedtime. Blue light emitted by screens affects the secretion of melatonin (sleep hormone) and, consequently, has an impact on your biological clock.
  
• Try to be as regular as possible by going to bed and getting up at the same time every day, even at weekends.
  
• Listen to your body. As soon as you feel the first signs of sleep (yawning, drowsiness...), it's time to go to bed!
  
• Create an environment that favours falling asleep: room temperature at 18 degrees and no television. Your bedroom should be a room reserved solely for sleep.
  
• Maintain regular physical activity. Sport helps you get tired and therefore fall asleep better. However, avoid intense physical activity in the 3 hours that precede your bedtime as it can have the opposite effect.
  

Finally, if you have great difficulty falling asleep or suffer from insomnia, do not hesitate to make an appointment with your GP who will be able to refer you to a specialist if necessary.