A midday nap can be a refreshing way to recharge and comes with many noted benefits. But for some people, napping too long or too soon after eating can make them feel disoriented, sluggish, or even nauseous—in a word, sick.

Knowing why naps can make people feel sick can help them take steps to get the most out of naptime. 

Why You Can Feel Sick After Napping

There can be many reasons why someone might feel sick after a nap, not all of which may be directly related to napping. Pregnancy, dehydration, and infection are just some of the reasons a person may feel unwell upon rising from a nap. But for people without such conditions, the answer may lie in the amount of time they spend napping.

In general, the longer a person naps, the more likely they are to feel woozy, foggy, groggy, or even nauseous when they get up. This is because longer naps increase the chances of sleep inertia or acid reflux.

What Is Sleep Inertia?

Sleep inertia is the groggy, disoriented feeling that can accompany waking up. People with sleep inertia may be drowsy, move slowly, have impaired reaction times, or find their thinking to be fuzzy. They may not feel fully awake and may also have a strong wish to go back to sleep.

Sleep inertia tends to be more common after longer naps, such as those lasting more than 30 minutes . After a longer nap, these feelings can last from 20 to 30 minutes, but they can last even longer if a person has not been getting enough sleep regularly .

What Causes Sleep Inertia?

There is no consensus yet for why sleep inertia occurs, but researchers have developed several compelling theories. Among them is the idea that sleep inertia results from being awakened during deep sleep and having the sleep cycle interrupted.

During a night’s sleep, a sleeper passes through four stages of sleep in each one of several sleep cycles. These stages can be separated into non-rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep. NREM sleep has three stages, the third of which is called deep sleep or slow-wave sleep.

Deep sleep is important for healing, immune function, long-term memory, and general refreshment. It is also harder for a person to awaken from deep sleep. The longer a person sleeps—or naps—the more likely it is that they will enter deep sleep and experience sleep inertia upon waking.

On the other hand, shorter naps of less than 30 minutes can increase a person’s alertness in the short term and are less likely to cause grogginess or confusion. 

What Is Acid Reflux?

Acid reflux is a backup of the stomach’s contents, including stomach acids, into the esophagus. It may also be called gastroesophageal reflux or heartburn. Acid reflux is a common cause of nausea and can also cause a burning, painful sensation in the chest. 

While virtually everyone has some acid reflux now and again, some people experience reflux frequently enough to be diagnosed with a disorder called gastroesophageal reflux disease (GERD). GERD can cause damage to the esophagus’s inner lining and may lead to serious medical conditions including esophageal cancer, if it is not kept under control.

“GERD can be treated with over-the-counter medications. However, if GERD symptoms do not improve or persist, a person should seek medical help and be evaluated.”

Dr. Anis Rehman, Internal Medicine Physician

People may experience acid reflux while they sleep for several reasons. 

  • Lying down: When a person is awake and upright, gravity helps keep the contents of the stomach in place. But when they lie down to nap or sleep, that is no longer the case. 
  • Decreased saliva production: Saliva helps neutralize stomach acids that find their way into the esophagus. But during sleep, a person produces much less saliva than when they are awake.
  • Reduced swallowing: The swallowing reflex also keeps stomach acid out of the esophagus, but people swallow much less often when they are asleep.

Acid reflux can happen not just during nighttime sleep, but while a person is napping as well. One study found that, among people already prone to the condition, acid reflux was even more common during naps than during overnight sleep. 

Research has also demonstrated that deep, slow-wave sleep increases the risk of acid reflux. This means that napping long enough to enter deep sleep could result in nausea or heartburn upon rising from the nap.

Tips to Improve Your Naps and Wake Up Easier

If you enjoy taking naps but feel sick or groggy afterwards, you may not need to give up napping. Instead, you can take steps to keep that post-nap sick feeling under control.

  • Keep your naps short: Naps longer than 30 minutes increase the chance of sleep inertia, while naps as short as 10 minutes have been proven to convey many benefits. You can set an alarm if you think you will nap too long.
  • Give yourself time to recover: Anticipate that you will need some time once your nap is done to overcome any sleep inertia that may follow. Try not to perform complicated tasks or those requiring a great deal of concentration right after waking up. 
  • Help yourself wake up: You can shake off sleep inertia by going out into the sunshine, splashing cold water on your face, or having some coffee or tea at hand to drink right after you get up. 
  • Watch what and when you eat: Spicy and acidic foods, fatty meals, and alcohol all raise the chance of acid reflux occurring during your nap. Also, if possible, wait some time after your midday meal before taking a nap.
  • Make it a coffee nap: A coffee nap may help you avoid feeling groggy when you wake. For a coffee nap, ingest about 100 milligrams of caffeine, the amount normally found in an 8-ounce serving of coffee. Then, directly afterward, lie down to nap. Since caffeine takes about 30 minutes to affect you, it should fully kick in right after you wake up. 
  • Try to get enough sleep each night: If you are sleep deprived, you may enter deep sleep earlier in your nap than if you got sufficient sleep the night before. This means you may experience sleep inertia even after a short nap. Sleep deprivation can also make post-nap sleep inertia last longer and can increase the chances of daytime nausea

If you are nauseous or have heartburn frequently after napping, you may want to talk to your doctor. Your doctor can advise you on lifestyle changes you can make to help manage acid reflux. They may also be able to prescribe medications or recommend other interventions that could help.

Learn more about our Editorial Team

6 Sources

  1. Maski, K. (2022, May 23). Insufficient sleep: Evaluation and management. In T. E. Scammell (Ed.). UpToDate.

  2. Hilditch, C. J., & McHill, A. W. (2019). Sleep inertia: Current insights. Nature and Science of Sleep, 11, 155–165.

  3. National Institute for Occupational Safety and Health. (2020, March 31). Nap duration. Centers for Disease Control and Prevention.

  4. Nasrollah, L., Maradey-Romero, C., Jha, L. K., Gadam, R., Quan, S. F., & Fass, R. (2015). Naps are associated more commonly with gastroesophageal reflux, compared with nocturnal sleep. Clinical Gastroenterology and Hepatology, 13(1), 94–99.

  5. Lim, K. G., Morgenthaler, T. I., & Katzka, D. A. (2018). Sleep and Nocturnal Gastroesophageal Reflux: An Update. Chest, 154(4), 963–971.

  6. Mantua, J., & Spencer, R. M. C. (2017). Exploring the nap paradox: are mid-day sleep bouts a friend or foe? Sleep Medicine, 37, 88–97.


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