According to the Centers for Disease Control and Prevention (CDC), adults need more than 7 hours of sleep per night, and children ages 6 to 12 need 9 to 12 hours for optimal health.

But life is busy, and getting an adequate amount of sleep isn’t always possible, especially when you’re traveling, cramming for an exam, or raising young children. A 2014 nationwide survey found that about 35 percent of Americans don’t get the recommended 7 hours.

If you’ve found yourself up in the waking hours of the morning trying to decide whether to sleep for a couple of hours or to just stay up, you should opt to sleep. Here’s why.

If you’re in a situation where you’re trying to decide whether you should sleep for a couple of hours or not at all, neither option probably seems appealing. However, getting some sleep is better than getting none.

Sleep is the period when your body repairs its tissues, replenishes hormones, and transfers short-term memories into long-term memories. If you skip a night’s sleep, your mental function and mood will significantly decline the next day.

According to the CDC, being awake for 18 hours causes a similar mental impairment as having a blood alcohol content of 0.05 percent, and being awake for 24 hours is equivalent to 0.10 percent. Skipping sleep is an equivalent to being drunk.

While you’re asleep, your body cycles through four stages of sleep roughly every 90 minutes, and on a normal night, you get 4 to 6 of these cycles. Sleeping for a couple of hours or fewer isn’t ideal, but it can still provide your body with one sleep cycle.

Ideally, it’s a good idea to aim for at least 90 minutes of sleep so that your body has time to go through a full cycle. Research has found that sleeping for 90 to 110 minutes may help reduce grogginess when you wake compared to shorter 60-minute sleeping sessions.

The four sleep stages can be divided into two categories: rapid eye movement (REM) and non-rapid eye movement (NREM). NREM makes up about 75 to 80 percent of your sleep.

  • Stage 1 (NREM). Stage 1, called N1, is the lightest stage of sleep and lasts for about 1 to 5 minutes. Your brainwaves, breathing, and heart rate all begin to slow, and your muscles relax.
  • Stage 2 (NREM). In stage 2, which is called N2, your body temperature drops while your heart rate and breathing continue to slow. Stage 2 lasts for about 25 minutes in your first sleep cycle and gets longer with each additional cycle.
  • Stage 3 (NREM). Stage 3, also called N3 or deep sleep, is when your body repairs itself and strengthens your immune system. Even loud noises may not wake you from this stage of sleep.
  • Stage 4 (REM). REM sleep is the cycle where you’re most likely to dream and is characterized by paralyzed muscles and quickly moving eyes. It usually begins about 90 minutes after you fall asleep, and during each cycle throughout the night, it gets longer.

Sleepiness is regulated by two processes: your circadian rhythm and sleep pressure.

Your circadian rhythm is your body’s internal clock that makes you feel tired at night and awake during the day. Sleep pressure is a feeling of tiredness that gets stronger the longer you stay awake. If you don’t sleep, your drowsiness will continue to get worse until you can finally get some rest.

Sleeping for 1 to 2 hours can decrease sleep pressure and make you feel less tired in the morning than you otherwise would by staying up all night.

If you don’t get enough sleep, you’ll likely experience:

Sleep deprivation can negatively impact your judgment and your ability to assess your cognitive ability. Not getting enough sleep puts you at risk of making poor decisions such as driving when not mentally alert.

Regularly getting less than 6 hours of sleep increases your risk of falling asleep at the wheel by 260 percent compared to regularly getting 7 to 9 hours. Sleepy driving also accounts for about 1 in 6 fatal crashes.

Not getting adequate sleep over a long period can negatively impact a variety of aspects of your health. Chronic sleep deprivation puts you at a heightened risk of developing:

If you’re in a situation where you have to choose between getting very little sleep or getting none, it’s better to opt for some sleep.

Ideally, you should try to get more than 90 minutes of sleep. Sleeping between 90 and 110 minutes gives your body time to complete one full sleep cycle and can minimize grogginess when you wake.

But any sleep is better than not at all — even if it’s a 20-minute nap.

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