How Much Sleep Do I Really Need?

“Sleep affects every organ system and bodily function, from your heart to your brain, and even the way that you think and feel each day,” says Emerson Wickwire, a sleep medicine specialist at the University of Maryland Medical Center.

Whether you work the night shift, follow an irregular sleep schedule or have a sleep disorder, such as sleep apnea or insomnia, that inhibits you from getting quality rest, getting less sleep than you need can prevent restorative processes from occurring. This includes muscle recovery, hormone regulation, immune functioning and memory consolidation.

“During sleep, the immune system produces protective mechanism antibodies and cytokines which help combat infections from viruses, bacteria and other illnesses,” says Dr. Fouzia Siddiqui, a neurologist and sleep center medical director at Sentara Health.

[READ Why Can’t I Sleep When I’m Stressed?]

How Much Sleep Is Enough?

On average, most adults require about seven to nine hours of sleep each night, but more than 1 in 3 American adults say they fall below this recommended number.

“Contrary to popular belief, sleep is an extremely active process, rather than a perceived shutdown of the body, as the brain and body go through critical maintenance,” says Dr. David Benavides, a board-certified sleep medicine physician at Harvard Medical School & Mass General Brigham.

That’s why it’s crucial for the body to get good, quality rest.

The National Sleep Foundation provides recommendations for certain age groups based on the needs of each population. For example, babies and children often need more sleep to support their rapid growth and development.

^{Note: These guidelines are often designed for people without underlying health conditions, sleep disorders included. Talk to your health care provider about how much sleep may be best for you.}

[READ: How to Sleep Better.]

What Happens If You Don’t Get Enough Sleep?

Sleep deprivation, also called sleep insufficiency, occurs when someone regularly gets less sleep than their body needs. This happens either because they don’t get enough sleep or their sleep quality is poor.

Some people experience sleep deprivation temporarily, while for others it may be more chronic, persisting for years..

Sleep deprivation can affect everyone, but certain groups are more susceptible than others. These include:

— Adults

— Teenagers

— Women

— Caregivers

— New parents

— Shift workers

Sleep deprivation vs. insomnia

While sleep deprivation and insomnia may seem like similar conditions, there are a few differences between the two.

Sleep deprivation refers to not getting enough sleep, either because you don’t allow yourself enough time to rest due to work demands or lifestyle, or because you don’t practice habits that promote quality, restful sleep, referred to as sleep hygiene.

Insomnia, on the other hand, is a clinical sleep disorder that makes it difficult or impossible to fall and stay asleep, despite feeling exhausted and carving out the time to get enough sleep.

[READ: Acupuncture for Insomnia: How Acupuncture Can Help You Sleep.]

Health Effects of Poor Sleep

Not getting enough sleep can affect your health in a multitude of ways, both physically and mentally.

Physical health effects

Chronic sleep deprivation can increase the risk of the following:

— Cardiovascular disease

— Heart attack

— Stroke

— Obesity

— Type 2 diabetes and insulin resistance

— Metabolic syndrome

— Weakened immune system

“Chronic sleep loss weakens the immune system and raises inflammation, which can make you more prone to infections,” says Dr. Gunjan Narwani, a neurologist at Houston Methodist Clear Lake Hospital.

Mental and cognitive health effects

Those who don’t get adequate sleep are more likely to experience the following:

— Impaired cognition (poor memory and slow decision-making, processing and reaction time)

— Anxiety

— Depression

— Issues staying attentive

As a result, sleep deprivation has been linked to an increased risk of car crashes. For example, a 2018 study found that sleeping about six hours per night was associated with a 33% higher crash risk compared to sleeping seven to eight hours.

“Much like drunk driving, we are pretty bad at recognizing when we are impaired due to not getting enough sleep,” Wickwire says.

Common Signs You’re Not Getting Enough Sleep

Even though sleep deprivation can cloud your judgment, there are still some clear signs that you’re not getting enough rest.

— Mood swings and irritability. You process emotions during sleep. When you don’t get enough rest, that emotional regulation is disrupted, which can lead to increased anxiety, frustration and a dampened mood. All of these factors can contribute to irritability.

— Unhealthy food cravings and irregular snacking. Sleep deprivation has a direct effect on hormones, specifically leptin and ghrelin — both of which play a role in regulating your appetite. When you don’t get enough sleep, your body reduces leptin production, which helps regulate your body weight, and increases ghrelin, which stimulates your appetite. Specifically, being sleep deprived can make you unconsciously crave high-sugar and fatty foods, according to research.

— Low energy. If you feel like you’re running on low energy all day, that’s a key sign you’re not getting adequate sleep. This can lead to daytime “microsleep” episodes, which are a few moments of falling asleep while sitting without even realizing it, and can be especially dangerous when you’re operating a vehicle.

— Impaired memory. If you find it challenging to stay focused and alert during the day or your work shift, that can impact your ability to remember information. While this may present as a short-term memory problem, Siddiqui says, in many cases, it’s a lack of sleep.

— More sick days. Are you regularly coming down with a cold? Can’t seem to shake a respiratory virus? You’re probably not sleeping enough. Research has shown that only getting around six hours of sleep may increase your risk of getting a cold, the flu and other infectious diseases.

How Can You Improve Your Sleep?

There are several ways you can enhance your rest each night. Some tips from experts include:

— Dedicate seven to nine hours for sleep

— Create a consistent sleep schedule (even on weekends and holidays for those who work Monday to Friday during the daytime hours)

— Develop a soothing pre-sleep wind-down ritual, like listening to relaxing music, doing deep breathing exercises or stretching

— Avoid using phones, tablets or watching TV within one hour leading up to sleep

— Dim the lights and consider lowering the temperature in your room before sleep

If you’re still struggling to sleep, you may need to schedule an appointment with your health care provider or a sleep specialist. They can help you get to the bottom of your sleep issues and create an action plan for how to get better rest.

Bottom Line

Sleep deprivation affects a lot of American adults, as work and lifestyle demands can interfere with establishing consistent sleep schedules.

However, if you’re feeling more exhausted than usual, are struggling to stay alert or regularly forgetting information you just learned, these are all signs that your body needs more rest.

If you’re struggling to improve your sleep habits on your own, speaking with a physician can help you get back on track.

More from U.S. News

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How Much Sleep Do I Really Need? originally appeared on usnews.com

Update 06/04/25: This story was previously published at an earlier date and has been updated with new information.