Up late studying, or a new parent? Sometimes life calls and we don’t get enough sleep. But five hours of sleep out of a 24-hour day isn’t enough, especially in the long term.

According to a 2018 study of more than 10,000 people, the body’s ability to function declines if sleep isn’t in the seven- to eight-hour range. Researchers found verbal skills, reasoning skills, and overall ability to think weren’t at full capacity.

Seven to eight hours of sleep per night is needed to perform your best at:

  • communicating
  • planning
  • decision-making

Many of us aren’t getting enough sleep. According to the Centers for Disease Control and Prevention (CDC), more than one-third of American adults are not getting enough sleep on a regular basis.

The National Sleep Foundation’s sleep time duration recommendations for healthy people without sleep disorders are as follows:

  • Newborns: 14 to 17 hours
  • Infants: 12 to 15 hours
  • Toddlers: 11 to 14 hours
  • Preschoolers: 10 to 13 hours
  • School-aged children: 9 to 11 hours
  • Teenagers: 8 to 10 hours
  • Young adults: 7 to 9 hours
  • Adults: 7 to 9 hours
  • Older adults: 7 to 8 hours

The immediate symptoms of sleep deprivation include:

Symptoms worsen the longer you go without sleep. You may even experience hallucinations.

There are a number of health risks associated with sleep deprivation, including:

  • Brain performance similar to aging. A 2018 study looked at severe sleep deprivation (no more than four hours a night). Researchers found it resulted in a decline in thinking ability equivalent to adding nearly eight years in age.
  • Risk of diabetes. A 2005 study found that sleeping too little (six hours or less) is associated with increased risk of diabetes. Sleeping too much (nine hours or more) was also associated with this increased risk.
  • Early death. A 2010 review and meta-analysis found that sleeping too little at night increases the risk of early death.
  • Risk of stroke or heart disease. A 2011 review of 15 studies found that people who sleep fewer than seven hours per night have a far greater risk for stroke or heart disease than people sleeping seven to eight hours per night.

According to the American Academy of Sleep Medicine, a lack of sleep is commonly caused by:

  • Underlying health conditions. An ongoing sleep disorder or other condition can disturb sleep.
  • Behaviorally induced insufficient sleep syndrome (ISS). This is the medical term for choosing to delay sleep to participate in another activity, like watching TV.
  • Employment obligations. Long or irregular hours can affect your sleep schedule. Some people may develop shift work sleep disorder.
  • Personal obligations. Examples include bringing a new baby home or providing care for an adult.

Sleep is critical for good health. Not getting enough sleep can lead to diminished brain performance and, in the long term, greater risk of health conditions. These include heart disease, stroke, and diabetes.

Aim to get seven to eight hours of sleep every night. To help you sleep well, practice good sleep hygiene.