How much sleep do we need and why is it important?
We spend about a third of our lives sleeping.
As a whole, the amount of sleep needed depends on age and health. Sick people may need to sleep more, but for healthy people it should be between 7 to 9 hours. Insufficient sleep is considered a public health problem, and may lead to chronic health conditions and mood disorders.
Scientists couldn’t quite figure out why we need so much sleep.
We do know that sleep is not a waste of time in the first place, so read on to discover why you need it.
Table of Contents
- 1 How much sleep do we need? Introduction
- 2 How much sleep do we need exactly?
- 3 The consequences of not sleeping enough
- 3.1 Lack of sleep makes us more distracted
- 3.2 Increased risk of anxiety and depression
- 3.3 Exaggerated emotional response
- 3.4 More cravings and increased blood sugar
- 3.5 Weaker immune system
- 3.6 Sleep deprivation accelerates the aging process
- 3.7 Increased risk of heart attack
- 3.8 Reduced stamina
- 3.9 The connection between sleep and our gut microbiome is a two-way street
- 4 How much sleep do we need? Conclusion
How much sleep do we need? Introduction
During our sleep, our bodies and brains are busy with all kinds of processes:
- clearing waste products,
- processing information we have absorbed during the day,
- making growth hormones,
- repairing tissue, etc.
The saying “sleep on it” is a folk wisdom pearl that is thus confirmed by scientific research.
How much sleep do we need exactly?
In normal circumstances, 7 to 9 hours of sleep are sufficient. The exact duration varies from person to person. But to get to those 7 hours, you actually need to be in bed at least half an hour longer.
Moreover, 7 hours is the minimum; 8 to 8.5 hours proves even better and is advanced by experts as the recommended duration.
Your mileage may vary
However, there are significant individual differences. For example, older people sleep less and have less need for it. In contrast, children and sick people or are at risk of being ill need more sleep.
This has to do with the sleep functions such as recovery, growth, immunity, etc. Sleeping too long can also be problematic, by the way.
Sleep is not so much about quantity, the number of hours we sleep, but the quality of sleep counts. This can be reduced, for example, by alcohol, drugs, or medication.
Try to avoid sleeping pills
A good rule of thumb is to avoid sleep aids and certainly not take them for more than a few weeks.
Sleep aids may allow you to sleep a little longer (minutes rather than hours), but that doesn’t mean you’ve slept well and are rested and fit.
Unless you suffer from a specific medical condition where sleeping pills are indicated, a good lifestyle should be enough to enjoy a good night’s sleep.
The sleep cycles
Before the discovery in 1929 of the encephalogram or EEG, which detects electrical activity in the brain, sleep in our brains was believed to be a period of relatively little activity.
This turns out to be false; instead, numerous complex and dynamic processes take place during our sleep.
When we sleep, our brain goes through a series of sleep cycles that last about 90 minutes each. Each cycle consists of several phases with their own characteristics:
- our brain goes from light sleep
- to deep sleep, and
- then reaches the stage of REM sleep (Rapid Eye Movement), the stage where we dream.
Every stage of our sleep is important, but research shows that a lack of REM sleep, in particular, hurts our performance and ability to learn.
We sleep ever less
Unfortunately, many people’s current lifestyle is not exactly sleep-friendly.
While we still slept an average of nearly 8 hours a night in the 1950s, that has reduced to only 6.5 hours. Over the past century, our sleep duration has shrunk by as much as 20%.
Meanwhile, most of the population suffers from chronic sleep deprivation, which is a life-changing problem.
As a result, the US Centers for Disease Control and Prevention (CDC) has declared that insufficient sleep is considered a public health problem.
Read on to find out why that is through an overview of the negative health effects of sleep deprivation.
- Hafner, et al., Why Sleep Matters-The Economic Costs of Insufficient Sleep: A Cross-Country Comparative Analysis, Rand Health Q, 2017
The consequences of not sleeping enough
Sleep deprivation is a stressor for the body and mind with effects similar to those induced by stress.
Below is an overview of negative health effects of insufficient sleep.
Lack of sleep makes us more distracted
A lack of sleep makes us less alert, which dramatically increases the risk of accidents in traffic and at work when using machines and equipment.
Because sleep deprivation leads to more accidents and lower productivity, we lose an estimated 2.28% of the gross national product due to collective sleep deprivation.
Increased risk of anxiety and depression
Sleep deprivation is also linked to anxiety and depression.
Those with little sleep are more likely to experience depression and even suicidal thoughts.
Exaggerated emotional response
Sleep deprivation also has an effect on our emotions. For example, when we are well-rested, the prefrontal cortex, the brain region where typical human thinking occurs, keeps our emotions pretty much in check.
However, when overtired, the functioning of that prefrontal brain decreases sensitively.
One result is that we are more likely to perceive information as threatening and react more violently to negative stimuli.
More cravings and increased blood sugar
Sleep deprivation also has indirect effects, such as making you eat more.
Those who do not sleep enough have stronger cravings for sweets and fat.
Sleep deprivation also raises blood sugar levels.
Weaker immune system
Our immune system also suffers from sleep deprivation. If you slept less than five hours, you are five times more likely to catch a cold the next day.
This may seem harmless, but the number of so-called natural killer cells, a type of white blood cell, also drops dramatically.
In one night of four hours of sleep, researchers saw a 70% decrease in these immune cells, which are used to fight viruses and cancer cells, among other things.
Sleep deprivation is therefore also an additional risk factor for developing cancer.
- Prather, et al., Behaviorally Assessed Sleep and Susceptibility to the Common Cold, Sleep, 2015
- Gaoatswe, et al., Invariant Natural Killer T Cell Deficiency and Functional Impairment in Sleep Apnea: Links to Cancer Comorbidity, Sleep, 2015
Sleep deprivation accelerates the aging process
People who sleep poorly have shorter telomeres on average.
These substances are at the end of our chromosomes and play an essential role in aging.
Increased risk of heart attack
One night of little sleep won’t give you a heart attack, but chronic sleep deprivation strains the heart, and then one bad night can sometimes be enough to trigger a heart attack.
We know this because every year, there is a kind of “natural experiment” in which the entire population sleeps one hour less: the switch to summertime.
With this switch, the rate of myocardial infarction increases by 24% the next day.
With the switch to the winter hour six months later, when we are allowed to sleep an hour longer again, the number of infarctions drops again by 21%.
Even those who want to perform sports need a good night’s sleep.
Namely, one night of insufficient sleep can reduce our stamina by 30%!
The connection between sleep and our gut microbiome is a two-way street
It has also recently become clear that the bacteria that populate our guts play a role in the digestion of food and may also be linked to sleep.
If you have sleep problems, it is helpful to pay attention to the microbiome, of which the bacteria in the intestines make up the bulk.
Moreover, our gut bacteria also appear to have a circadian rhythm and thus influence our sleep. Similarly, our circadian rhythm can be disturbed by what we eat.
How much sleep do we need? Conclusion
Sleep deprivation, like poor nutrition, excessive stress, lack of exercise, and social interaction, works on the basic mechanisms of our health.
Every system in our body can be affected by it. It should therefore come as no surprise that sleep deprivation fuels just about all chronic diseases, as well as infectious diseases:
- mood disorders,
- cardiovascular disease,
- anxiety, and ultimately
- premature death.
So, make sure you get at least 7 hours of sleep per night! If you can manage 8 to 8.5 hours, even better!