Medically reviewed by
Dacelin St Martin, MD
Triple board-certified in Sleep Medicine,
Internal Medicine, and Pediatrics.
You’ve probably heard many times that sleeping less than 7-8 hours a night can be bad for your health.
Sleep is essential for the brain to operate well as it’s needed to regulate nearly all physiologic and mental functions. Indeed, sleep deprivation can have many dire effects on your health and mood.
In the short term, it can cause decreased concentration, memory troubles, sleepiness, and irritability during the day.
In the long term, the effects of sleep deprivation can be catastrophic. It can increase your risk of diabetes, obesity, heart disease, stroke, and other dangerous illnesses.
As a result, chronically sleep-deprived patients are more likely to die earlier than those who get a full night’s sleep.
What Defines Sleep Deprivation?
Sleep deprivation is a general term used to describe sleeping patterns with less than the recommended sleeping hours.
There’s no clear-cut limit that determines when someone is sleep-deprived. If you’re sleeping less than the recommended time for weeks or months, you’re usually considered sleep-deprived by sleep doctors.
Sleep deprivation is sometimes used interchangeably with “sleep insufficiency” or “sleep deficiency.” These are more precise terms that take sleep quality into consideration when determining if you’re sleep-deprived or not.
For example, if you have obstructive sleep apnea (OSA) syndrome, you can be sleep deprived even if you sleep for 8 hours. Such patients have low sleep quality, so 8 hours of sleep accounts for much less.
How Many Hours Should You Sleep Daily?
The amount of recommended sleep is based on the age group. In general:
- Babies: 12 to 17 hours a day
- Toddlers: 11 to 14 hours a day
- Children: 9 to 13 hours a day
- Teens: 8 to 10 hours a day
- Adults: 7 to 9 hours a day
If you’re sleeping even 1 hour less than the daily recommended sleep time, you’re not sleeping enough. You’re putting yourself at risk of sleep deprivation and are at increased risk of morbid illness.
Effects of Sleep Deprivation
Sleep is crucial for almost every single physiologic function in our body. While asleep, the body, in a sense, repairs itself and prepares for a new day.
Physiologically, this is why sleep deprivation can have disruptive effects on all body systems, with long-term sleep disruptions having more serious consequences on the body.
- Altered Cognitive Abilities
Sleep deprivation takes the most obvious toll on your brain. Poor concentration is a tell-tale sign you’re not getting enough sleep.
Many sleep specialists theorize that memories are inscribed into the brain when you sleep – a process called memory consolidation.
Whatever you learn during the day, the brain saves it permanently when you sleep. If you’re sleep-deprived, your brain will not complete this process.
This physiological response is why poor memory is a common sign of sleep deprivation. Similarly, sleep deprivation will cause decreased problem-solving abilities, alertness, and reasoning. Simply put, it diminishes your mental capacity.
- Daytime Sleepiness and Fatigue
Daytime fatigue is a common short-term sign of poor sleep quality and sleep deprivation. If you’re not getting enough sleep at night, your body will try to compensate.
Poor sleep manifests as daytime sleepiness, fatigue, and falling asleep when you’re not supposed to (e.g., at work or watching TV).
- Increased Risk of Serious Illnesses
Research has shown that those who are sleep deprived are at a significantly increased risk of developing one or more serious conditions, like:
- Heart disease
- High blood pressure
- Arrhythmia 
- Decreased Libido
One of the effects of sleep deprivation in men is a decreased sex drive, which is caused by a disruption of testosterone production.
Production of testosterone requires at least 3 hours of continuous sleep. Interrupted or poor sleep can lead to low testosterone levels and significantly cause a low sex drive.
- More Signs of Aging
Signs of skin aging, like wrinkles, eye bags, dark patches, and frown lines, develop more rapidly if you don’t sleep well enough. Sleep deprivation leads to increased cortisol release and decreased growth hormone.
High cortisol damages collagen, an essential skin protein responsible for elasticity and firmness. Low growth hormone, on the other hand, means less cellular regeneration. The result is rapid skin aging.
- Higher Overall Mortality Risk
Sleep deprivation can take years off of life. One study in the UK has shown that sleep-deprived people are two times more likely to have cardiovascular disease.
- More Weight Gain
Lack of sleep can disrupt the balance between leptin and ghrelin, two hormones that control your appetite. This imbalance makes you eat more and subsequently gain more weight.
One study has shown that those who sleep less than 5 hours a day are 40% more likely to suffer from obesity than those who sleep the recommended hours.
- Depression and Mental Disorders
Sleep disorders and mental illness have a bidirectional relationship. This term means that insomnia can lead to poor mental health, and mental disorders can lead to insomnia and sleep deprivation.
According to research, people who battle with insomnia have a five times higher risk of being depressed.
- Decreased Immunity
When you’re sleeping, your immune system replenishes its resources and rebuilds its fighting arsenal. Sleep deprivation, however, can disrupt this process.
If you’re not sleeping enough, your immune system will not produce essential defensive proteins, like specific cytokines and antibodies.
- More Risk of Accidents
According to estimates, sleepiness is responsible for one in every five accidents. This physiological response compromises your ability to focus while driving, increasing the likelihood of car accidents. Indeed, sleep deprivation can make you drowsy and affect your concentration.
Sleep deprivation has many effects, and it doesn’t just end with feeling sleepy the next day.
An unhealthy sleeping pattern can lead to severe chronic conditions and deadly accidents, which is why you should prioritize your sleepover and everything else.
If you suspect that you might be having sleep troubles, do not delay consulting with a sleep specialist to get a suitable treatment plan.
- Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation’s updated sleep duration recommendations: final report. Sleep Health. 2015;1(4):233-243. doi:10.1016/j.sleh.2015.10.004
- Klinzing JG, Niethard N, Born J. Mechanisms of systems memory consolidation during sleep. Nat Neurosci. 2019;22(10):1598-1610. doi:10.1038/s41593-019-0467-3
- Grandner MA, Jackson NJ, Pak VM, Gehrman PR. Sleep disturbance is associated with cardiovascular and metabolic disorders. J Sleep Res. 2012;21(4):427-433. doi:10.1111/j.1365-2869.2011.00990.x
- Cho JW, Duffy JF. Sleep, Sleep Disorders, and Sexual Dysfunction. World J Mens Health. 2019;37(3):261-275. doi:10.5534/wjmh.180045
- Hirotsu C, Tufik S, Andersen ML. Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Sci. 2015;8(3):143-152. doi:10.1016/j.slsci.2015.09.002
- Ferrie JE, Shipley MJ, Cappuccio FP, et al. A Prospective Study of Change in Sleep Duration: Associations with Mortality in the Whitehall II Cohort. Sleep. 2007;30(12):1659-1666.
- Xiao Q, Arem H, Moore SC, Hollenbeck AR, Matthews CE. A large prospective investigation of sleep duration, weight change, and obesity in the NIH-AARP Diet and Health Study cohort. Am J Epidemiol. 2013;178(11):1600-1610. doi:10.1093/aje/kwt180
- Baglioni C, Battagliese G, Feige B, et al. Insomnia as a predictor of depression: a meta-analytic evaluation of longitudinal epidemiological studies. J Affect Disord. 2011;135(1-3):10-19. doi:10.1016/j.jad.2011.01.011