Here’s What Happens to Your Immune System When You’re Short on Sleep

If you’re hoping to avoid getting sick, you’re going to want to make sure you’re getting decent shut-eye every night.

Photo: Gizela Glavas/

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You’re armed with hand sanitizer, you’re keeping your distance from anyone with the sniffles, you’re eating foods for a healthy immune system – but are you getting enough sleep? It’s easy to overlook sleep when you’re trying to build immunity and ward off colds or illnesses. But it’s hard to stay healthy if you’re short on sleep. Missing out on truly restful sleep can hamper your immune system in some surprising ways.

When your head hits the pillow each night, you’re doing more than resting and resetting for the next day. Your body is getting down to some of its most crucial work: Restoring, refreshing and healing work that can’t be performed while you’re awake and running full-speed throughout the day. So, when you aren’t getting enough sleep, you can hamper your health and wellness. And ultimately, you could have a negative effect on your immune system’s ability to prevent illness.

Here’s a peek at what takes place while you’re fast asleep, and why sleep is so important for a strong, healthy immune system. 

Your immune system works hard when you’re asleep

Sure, your nightly hours of sleep are restful (or so you hope!). But they’re also critically important for key body functions. As soon as you drift off to sleep, your body automatically gets to work – and many of its tasks are centered around your immune system.

While you’re asleep, your breathing and muscle activity slow down to free up energy for your immune system to get down to work. Cells are repaired, waste is removed and helpful hormones, like stress-counteracting melatonin, are released. You can think about it as a nightly sweep for potential ailments or problems, with your body doing “cleanup” to help you operate at your best in the AM.

Why can’t your immune system strengthen itself while you’re awake? Well, according to research, it’s because your body actually ramps up inflammation at night. In order to fight off potential intruders and illnesses, your immune system uses inflammation – and if this was to happen while you were awake, your physical and mental performance would be altered. It’s better (and more efficient) to do this work while you’re at rest.

Plus, your immune system’s activities are nicely self-regulated. Although a lot of activity, including an increase of inflammation-altering cytokines, is happening, your body knows what to do. And as morning arrives and you get ready to wake up, your natural circadian rhythm actually winds down that inflammation and brings you back into balance.

Sleep helps maintain your immune system’s natural balance

In order to carry out all of the reparative and restorative tasks your immune system performs during sleep, it needs to maintain a careful balance. It needs to not only identify and attack potential threats, but also keep you properly regulated to ward off those threats. So, your immune system has to be able to determine when to go full-on in protective mode, ramping up inflammation and bringing on symptoms like a fever or swollen lymph nodes, and when it should hold back.

The key to this balance? Consistent sleep.

According to research, sleep helps your immune system stay strong and finely-tuned. Every night of sleep contributes to your innate immunity and your adaptive immunity. Your innate immunity is your general immune system, which defends your body against foreign bodies, injuries and pathogens. Your adaptive immunity, on the other hand, kicks into action to protect against specific pathogens or changed cells. You can think of innate immunity as your first line of defense, while your adaptive immunity takes over to target specific threats. 

And while you’re asleep, research has shown that both of these immune functions kick in. Even if you aren’t actively sick or injured, your innate and adaptive immunity are working to strengthen your overall immune function. Plus, while you’re asleep, your immune system is fine-tuning its natural balance and reinforcing its own memory, which is key in its ability to recognize and react to potential threats.

Your immune system can’t protect itself when you’re missing out on sleep

With all of these important tasks happening while you’re resting in bed, it’s no surprise that missing out on sleep can have a negative effect on your immune system. And, as the Mayo Clinic sums it up, a lack of sleep can put you at an increased risk of getting sick.

Research shows that those who aren’t getting enough sleep – or enough quality sleep – are more likely to come down with the common cold or other viruses once exposed to them. In fact, a lack of sleep can even affect how quickly you’re able to recover from an illness when you get sick (and missing out on sleep means you’ll likely be sick for longer).

When you’re sleep deprived, even slightly, your immune system releases an increased amount of inflammatory cytokines. This higher-than-usual “dose” of cytokines is meant to help you combat stress. And your immune system also cuts back on its production of typical infection-fighting antibodies too. 

Additionally, a lack of sleep messes with another key immunity component: T cells. When your immune system recognizes an infection or virus, it automatically activates the production of integrins, or a protein that attaches to and kills infected cells. According to research conducted on the T cells of those who slept normally compared to sleep-deprived individuals, sleep deprivation resulted in lower levels of integrin. Getting proper sleep improved T cell functioning and made them better able to fight off would-be infections.

Both a short- and long-term lack of sleep can have noticeable effects on your health

The biggest takeaway about your immune system and sleep’s influence? When you’re not getting enough sleep, or enough wholly restful sleep, you’re likely going to have a negative effect on your natural immunity. And unfortunately, even short-term sleep deprivation can have an impact. 

The official sleep recommendation for adults is to aim for seven to eight hours of shut-eye per night. When you get less than this, you may be increasing your stress level, your adrenaline and your immune system’s fight-or-flight response. How much sleep, exactly, is too little for good immune health? Less than five hours on a regular basis has been found to be linked to higher mortality.

But even getting less than seven hours of sleep per night might have an effect. Some research has suggested that sleeping less than seven hours nightly for multiple nights in a row can be equal to whole nights of missed sleep. 

Whether you’re missing a night here or there or you’re experiencing more serious sleep deprivation, both are problematic. In the short-term, you may see effects like sleepiness, mood changes, mistakes and memory problems. Over the long-term, you can experience health concerns like inflammation, high blood pressure, an increased risk of heart disease and weight gain. And all of those might potentially be linked to how a lack of sleep disrupts your immune system’s natural functioning.

Try these sleep tips to help your immune system and your daily energy levels:

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