We’ve all been there: At the first sign of a cold, the flu, or another illness, our bodies seem to start craving extra sleep. You may find yourself especially struggling to get out of bed in the morning, nodding off for a necessary nap midday, or just lounging on the couch for longer than usual. It feels like your body is telling you to take a step back from your day-to-day life… but why does being sick make you tired?

The reason why you sleep so much when you’re sick is because of both the body’s response to being sick and the process necessary to recover. (After all, there’s a reason, “Get some rest!” is such a common refrain when someone says they’re under the weather!) “It is absolutely normal to need more sleep when sick,” says psychiatrist Allie Sharma, MD, co-founder and chief medical officer of mental health practice Being Health. “Your body is wired this way.”

Sickness puts our immune system in a weakened state, “as it works to fight off the infection,” explains Dr. Sharma. That just makes it all the more important to get good sleep when you’re sick, she says, not only to help facilitate the body’s ability to heal but also to protect yourself from further illness.

Does a cold make you tired?

A cold, the flu, or any other sickness can make you more tired than usual (and lead you to need more sleep), starting right around the time when you’re first getting sick.

As for why being sick makes you so tired? “Any acute viral infection causes a release from the body of inflammatory mediators, which can make us very drowsy,” says UCHealth pulmonologist and sleep specialist Neale R. Lange, MD. “It’s an instruction sent to our body to increase its temperature—which is why you’ll often get a fever in the first few days of being sick—because a higher temperature helps defend against the virus or bacterium.”

“Any acute viral infection causes a release from the body of inflammatory mediators, which can make us very drowsy.” —Neale R. Lange, MD, pulmonologist and sleep specialist

While that fever can make you feel sleepy, so can the pathogen (aka the virus or bacterium causing your sickness) itself. “As it circulates in the body, the toxin may be sleep-inducing, due to the extra effort necessary by your body to start fighting it,” says Nancy Foldvary-Schafer, DO, MS, director of the Sleep Disorders Center at the Cleveland Clinic.

All of that extra energy expenditure, in and of itself, can make you feel more tired as your body essentially works overtime to get over that cold, says Dr. Sharma.

The increased drowsiness is also your body telling you to put yourself to bed, so it can access the restorative effects of sleep. “All the stages of sleep, particularly the deeper non-REM and REM stages, have active functions,” says Dr. Foldvary-Schafer, “decreasing your heart rate and blood pressure, and also allowing for the immune response that clears away toxins.” And getting the most of these benefits requires sleeping more when sick.

Does sleeping help your immune system recover faster from illness?

It can be easy to dismiss the added hours of shut-eye you get while dealing with an illness as nothing more than “catching up on sleep,” but the reason why being sick makes you tired (and you might sleep so much when you’re sick) is actually tied to your body’s natural mode of recovery.

“Studies have shown that there is a direct correlation between sleep and our immune system¹,” says Dr. Sharma. Indeed, sleep is an “adaptive response,” she says, meaning that it plays a key role in helping the body fight infection².”

While you doze, your body can actually increase production of immune-supportive cytokine proteins (which help control inflammation in the body³) and more effectively shuttle infection-fighting T-cells to lymph nodes⁴, where they can get to work fighting your illness, says Dr. Lange. In fact, he adds, this is also why you need more sleep just before and after getting a vaccine, because doing so supports your body’s antibody-generating response (and, in turn, the vaccine’s efficacy). It also facilitates the movement of antibodies to the lymph nodes, where they reside.

Can extra sleep speed up the recovery process?

Extra sleep is one of the best defenses we have against illness, so it’s no surprise that it can also help speed up the recovery process when you’re sick.

“We are always exposed to pathogens that our immune system has to fight off,” says Dr. Sharma. “While we are slumbering, sleep helps to regulate and recuperate our immune systems, which enhances our ability to fight off these pathogens.”

So, while some people may see sleeping in or going to bed a few hours early when you’re sick as being lazy, part of the reason why being sick makes you tired is because extra rest can help you get yourself healthy again more quickly.

By contrast, not getting enough sleep can make getting over any sickness that much tougher. “The worse or more fragmented your sleep is, the higher your resting inflammatory condition will be,” says Dr. Lange, “and heightened inflammation just puts you more at risk for complications to arise from the illness.”

How much sleep to get when you’re sick

Every person’s drowsiness response to sickness will vary, meaning you should listen to your body to determine how much sleep you really need when you’re sick. “Do not try to override the sleepiness you feel,” says Dr. Lange, who stresses the importance of getting, at the very least, the recommended seven to eight hours of sleep while you’re sick, and allowing yourself to go up from there, depending on how drowsy you are throughout the day. And don’t be afraid to take advantage of naps, to help your body further rest and fight off infection.

As you begin to feel a bit better, you can continue extending your usual sleep by an hour or so each night for a few days, so long as you continue to wake up at the same time every morning, Dr. Foldvary-Schafer says. This helps re-regulate your circadian rhythm, while still allowing you to tend to your body’s temporary need for more shut-eye.

How to sleep well when you’re sick

If you’re someone with a consistent sleep schedule, it can be jarring to suddenly find yourself staying in bed for nine or 10 (or maybe even more) hours a night when you’re sick. But rest assured the extra sleep is proof that your body is working hard to get you back to health.

To get the quality sleep your body needs when you’re sick, it’s essential to both care for yourself and practice all the typical habits of healthy sleep hygiene:

• Eat something warm, like chicken soup, at least two hours before heading to bed to help clear your sinuses
• Avoid alcohol, which negatively affects sleep quality and suppresses the immune system⁵ (meaning it can make it tougher for your body to heal)
• Have a soothing, sleep-inducing drink, like chamomile tea or tart cherry juice, about an hour before your bedtime—not just to help yourself doze off but also to increase your hydration (which is known to support immune health)
• Steer clear of blue-light-emitting devices for about an hour before you’re planning to go to sleep (meaning, try not to doom-scroll while in bed)
• Get into bed earlier than usual to maximize your potential sleep time
• Use a warm-mist humidifier to relieve your congestion
• Take a warm shower before bed to boost your body’s natural melatonin production
• Make sure your bedroom is cool, dark, and quiet
• Prop yourself up with a wedge pillow to alleviate congestion and post-nasal drip
• Sleep alone, not just to prevent the spread of illness in your home, but also so that there’s no chance a partner disturbs the sleep you so desperately need, and so you can feel comfortable getting up to blow your nose and coughing if needed

How does sleep contribute to the immune response?

Sleep doesn’t just play a part in how we recover from illness; it can actually influence how we succumb to sickness as well. The effects of sleep deprivation (or having an inconsistent sleep schedule) can increase inflammation⁶ in the body, says Dr. Sharma, which then predisposes us to getting sick.

By contrast, “sleeping routinely and regularly will lower your vulnerability to becoming sick, and if you do get sick, sleeping well during the sickness will ensure that you are strengthening the immune system’s ability to fight off the infection,” says Dr. Sharma.

—medically reviewed by Angela Holliday-Bell, MD