How much sleep do we need each day?
This infographic shows that the number of hours of sleep required per night is inversely related to age and decreases with age. On the other hand, it varies little between the ages of 18 and 65.
These data represent an average, and each individual’s needs must be based on a variety of factors:
- How you feel after eight hours of sleep (e.g. for an adult)
- Specific health problems
- Number of calories burned each day (high or low)
- Level of alertness required for daily activities
- Whether or not you have problems sleeping
- Need for caffeine to get through the day
- Difference in hours of sleep between workdays and days off
The ideal amount of sleep varies from person to person, depending on their physiology and current situation.
However, while most adults have a good idea of how many hours they should be getting, there are a number of reasons why they may not be able to achieve this. And after too many sleepless nights, sleep deprivation builds up.
What is a sleep debt?
Does catching up on sleep help?
Mathematically speaking, it is entirely possible to recoup four or five hours of sleep by sleeping in on the weekend. But does this extra morning sleep have the same quality as nighttime sleep?
Not quite. When we try to make up for lost sleep, we are fighting our biological clock, and our sleep is not as restorative as if we had slept longer during the week.
In fact, when we shorten our amount of sleep, we may be depriving ourselves of certain sleep phases, such as deep sleep and REM sleep (the dreaming phase), which are important for many bodily functions, such as regenerating tissues, fighting infections, consolidating memories and regulating emotions. And our Saturday and Sunday sleeping binges will not necessarily make up for this shortfall.
According to a 2019 study from the University of Colorado, sleeping more on the weekend cannot prevent the metabolic disruption caused by repeated sleep deprivation. In other words, sleeping in doesn’t save our bodies from the consequences of hours lost during the week.
One of the main risks associated with catching up on sleep is the disruption of the body’s internal clock. The body secretes melatonin at the end of the day, which helps us fall asleep at night. By going to bed at irregular hours, we risk disrupting the production of this essential sleep hormone.
Similarly, waking up three or four hours later than usual can cause a jet-lag effect and further destabilize our biological clock.
Therefore, in case of fatigue, a short nap is generally preferable to a late awakening as it is less disruptive to the circadian rhythm.
Each hour of lost sleep increases the risk
To regulate sleep, your metabolism has a fundamental need for balance, but unlike an accounting balance sheet, it is not enough to reconcile assets and liabilities.
Alternating between short and long nights of sleep can eventually lead to metabolic disruption and serious illness. Sleep deprivation increases the likelihood of many physical and mental disorders, including:
- Cardiovascular disease
- High blood pressure
- Weakened immune system
- Alzheimer’s disease
Ten signs you may be suffering from sleep debt
The secret: a good sleep routine
For professional support, we’re here for you.
- Eric Sunni (mars 2021). «How Much Sleep Do We Really Need?», Sleep Foundation, https://www.sleepfoundation.org/how-sleep-works/how-much-sleep-do-we-really-need
- Christopher M. Depner et coll. (mars 2019). «Ad libitum Weekend Recovery Sleep Fails to Prevent Metabolic Dysregulation during a Repeating Pattern of Insufficient Sleep and Weekend Recovery Sleep», Current Biology, 29(6):957-967, https://www.cell.com/current-biology/fulltext/S0960-9822(19)30098-3
- Eric Sunni (juin 2021). «Sleep Deprivation: What it is, its causes, symptoms, and long-term effects on physical, mental, and emotional health», Sleep Foundation, https://www.sleepfoundation.org/sleep-deprivation
- David A. Kalmbach, J. Todd Arnedt, Vivek Pillai et Jeffrey A. Ciesla (mai 2015). «The Impact of Sleep on Female Sexual Response and Behavior: A Pilot Study», The Journal of Sexual Medicine, 12(5):1221-1232, https://www.jsm.jsexmed.org/article/S1743-6095(15)31025-0/fulltext