- A lack of
sleep can lead to manyhealth issues. - In the short-term, sleep deprivation can reduce memory and learning ability, increase your risk for harmful accidents, and lead to poor judgment.
- Long term, not getting enough sleep may increase your risk for heart disease, harm your
mental health , and make it more difficult to lose weight. - This article was medically reviewed by Alex Dimitriu, MD, psychiatrist and founder of Menlo Park Psychiatry and Sleep Medicine.
More than a third of Americans aren't getting enough sleep, according to the Centers for Disease Control and Prevention.
For optimal health, adults need at least seven hours of sleep each night. But depending on your age, you might need even more:
If you consistently lack sleep, it can pose serious health risks. In the short-term, staying awake for 17 to 19 hours straight can impair your reaction time as much as a blood-alcohol level of 0.05%, which is considered legally drunk. Long-term, a consistent lack of sleep may also increase your likelihood for a heart attack or mental illness.
Here are 6 ways a lack of sleep can negatively impact your health:
1. Impair your mental health
Insufficient sleep can affect your mood and increase your stress levels.
In fact, people with insomnia are 17 times more likely to develop clinical anxiety than people who aren't sleep deprived. Non-depressed people who have insomnia may be twice as likely to develop depression than people who sleep well.
This could be due to the impact that a lack of sleep has on the brain's ability to regulate emotions, which can lead to mood disturbances and negative thinking.
For example, a study published in Current Biology in 2007 examined healthy participants who were deprived of sleep for 35 hours. When the sleep deprived patients were shown negative images, they had more activity in the amygdala — the area of the brain that regulates emotions and anxiety levels — than participants who weren't sleep deprived.
In addition, research has found that 65% to 90% of adults with depression have sleep problems. While a lack of sleep can affect your mental health, depression can also cause insomnia, leading to a vicious cycle.
2. Reduce memory and learning ability
Researchers have found that just five hours of lost sleep in a 24-hour period can cut off the connection between neurons in the hippocampus, the area of the brain associated with memory.
In one small study published in the journal Neuroscience in 2005, 12 healthy college-aged participants were taught a sequence of finger movements and asked to repeat it 12 hours later as an MRI measured their brain waves.
Researchers found that the cerebellum, the area of the brain that controls accuracy, was more active in participants who had slept during that time period. This suggests that while you sleep, memory is shifted to more efficient storage areas in the brain.
A lack of sleep may also impair the brain's ability to flush out beta-amyloid, a toxic protein in the fluid between brain cells that has been linked to memory loss and Alzheimer's disease.
"Not sleeping enough at night will make it more difficult for you to learn or remember things later," says Raman Malhotra, MD, a sleep medicine physician and associate professor of neurology at Washington University School of Medicine. "Sleep helps imprint memories or things you are studying to try and remember in the future."
3. Make it more difficult to lose weight
Not getting seven to eight hours of sleep each night can activate your body's endocannabinoid (eCB) system, which increases your appetite for pleasurable but unhealthy foods, like candy and chips.
In one small study of 14 healthy young adults, published in the journal Sleep in 2016, researchers found that participants who got insufficient sleep for four nights had higher eCB levels in the afternoons than those who got a good night's sleep. The elevated eCB levels increased their appetites and their cravings for snacks.
"It can increase your urge to eat by altering the normal release and levels of different hormones responsible for hunger and satiety," Malhotra says. Research has also found that a lack of sleep increases the release of ghrelin, the hormone that stimulates your appetite, and decreases the release of leptin, the hormone that makes you feel full.
In addition, if you're not getting enough sleep, you may feel fatigue and not have the energy to exercise regularly, which can also contribute to weight gain. A small study of 15 healthy men, published in the American Journal of Clinical Nutrition in 2009, found that fewer hours of sleep for two nights in a row resulted in significantly decreased daytime physical activity.
4. Increased risk of heart disease
Getting less than seven hours of sleep each night can increase your risk of heart disease, heart attack, or stroke regardless of your age, weight, and whether or not you smoke or exercise, according to the National Sleep Foundation.
High blood pressure, or hypertension, is one of the major risk factors for heart disease. While you're getting a good night's sleep, your blood pressure should decrease about 10% to 20%, which is known as nocturnal dipping. But if you don't get the sleep you need, your blood pressure won't dip at night — and research has found that even small increases in your nighttime blood pressure level can lead to an increased risk of heart disease.
A consistent lack of sleep can also affect your body's ability to regulate stress hormones, and this chronic stress may contribute to a heart attack over time.
5. Cause harmful accidents
In 2017, there were an estimated 91,000 police-reported car crashes involving drowsy drivers in the US — about 50,000 people were injured and nearly 800 were killed.
Driving while drowsy is similar to driving under the influence. It slows down your reaction time and awareness of hazards, and reduces your ability to pay attention to what you're doing.
According to a study published in the journal Sleep in 2018, drivers who had fewer than four hours of sleep in the preceding 24-hour period were 15.1 times more likely to be responsible for a car crash than drivers who slept seven to nine hours during the same period.
Many work-related accidents are also attributable to insufficient sleep. Sleep-deprived workers are 70% more likely to have accidents on the job and twice as likely to die from those accidents than well-rested workers.
6. Lead to poor judgment
A lack of sleep can also result in poor judgment. This may be because sleep deprivation affects your brain's prefrontal cortex, the area that controls logical thinking. Examples include:
- People who are sleep deprived may be more likely to take risks. In one study published in the Annals of Neurology in 2017, participants could choose to either receive a certain amount of money or gamble for more money, but get nothing if they lost. Those who had fewer than five hours of sleep for a week were more likely to gamble than those who had eight hours of sleep.
- A lack of sleep may make you more impulsive. Research has found that this can make sleep-deprived people more likely to engage in aggressive behavior or lack self-control.
Sleep deprivation might also affect your moral judgment, because it impairs your brain's ability to use emotion and cognition to help you make decisions. Examples include:
- A lack of sleep can cloud an ethical decision-making process. For example, military personnel in combat may make choices they wouldn't have if they were well-rested, such as whether to harm or kill someone in order to save the lives of others.
- Sleep-deprived people may cheat more. Research has also found that participants who had slept just 22 minutes less than other participants the night before were more likely to cheat to win raffle tickets.
The bottom line
The adverse health effects of a single sleepless night can usually be mediated if you get better consistent sleep over the next few nights, Malhotra says. However, if you've been experiencing a chronic lack of sleep over multiple weeks, months, or years, you may be at a great risk of health problems that are more difficult to reverse.
Some sleep disorders, like insomnia or sleep apnea, will require medical treatment in order to fully resolve your sleep issues. If you think you are not getting enough sleep, consult with a physician or sleep specialist who can discuss treatment options.