Doctors warn this common sleep problem leaves you vulnerable during flu season — here's how to prevent it

On the left, a woman lies in bed blowing her nose because she doesn't feel well. On the right, a man sits on the edge of the bed in the dark with his head in his hands, feeling stressed and experiencing insomnia.

(Image credit: Getty Images)

Flu season is underway and as global levels of so-called 'super flu' rise, taking care of your health should be top priority. A new study published by Frontiers suggests a good night's sleep might help you avoid seasonal sickness, especially if insomnia and anxiety are plaguing your holiday season.

Key takeaways from the study

Participants experiencing Generalized Anxiety Disorder (GAD) showed lower NK cell count
This was even more prevalent in those with GAD and insomnia
As a result, people who are sleep deprived may struggle to fight viral infections

The study found people experiencing both GAD (Generalized Anxiety Disorder) and insomnia showed lower levels of NK (Natural Killer) cells than those without symptoms.

A type of white blood cell, NK cells are known to attack and destroy infected cells, including the influenza virus.

Woman in bed, blowing her nose — (Image credit: Andrea Piacquadio on Pexels)

"We found that in students with insomnia symptoms, count and percentage of total NK cells and their sub-populations were declined," author of the study Dr. Renad Alhamawi, assistant professor of immunology and immunotherapy at Taibah University, explained to Medical Express.

This isn't a new discovery — the link between good sleep and a healthy immune system is well established. However, the intersection with GAD is particularly relevant at this time of year as SAD and holiday stress can cause rising anxiety levels.

Dr. Alhamawi told Medical Express that students with GAD had a "lower percentage and number of circulatory NK cells and their sub-populations, compared to symptom-free students."

There are some liabilities to the study, primarily its lack of diversity (only young females were observed.)

However, for those who are often inclined to neglect their sleep during the busy holiday season, this study further reinforces the need for a good night's rest.

How poor sleep leaves you vulnerable to flu

“To recover from illness, your body needs deep, uninterrupted sleep," explains Dr. Menachem Jacobs, Resident Physician at Yale New Haven Hospital.

A study from 2011 noted the "specific role of sleep in the formation of immunological memory", observing that during the early sleep stages T cells, vital to the creation of an immune response, peak. And on a more anecdotal level, a 2018 survey found 95% of physician's believe a good night's sleep is important for cold/flu patients.

Woman sleeping on mattress with a pillow under her head in a cozy bedroom with warm lighting and a plant next to the bed — (Image credit: Future)

On the other hand, research from 2025 noted just a single night of poor sleep can negatively impact your immune system.

The study found that sleep deprivation altered the profile of monocytes, white blood cells vital to your immune system, among otherwise healthy individuals.

Sleep deprivation can also result in unhealthy choices: you're less likely to eat well and exercise when feeling tired. As a result, you might find your illness lingers, as your body lacks the support it needs to fight sickness.

5 ways to improve your sleep (and your immune system)

1. Keep your cool

While you might be tempted to cocoon yourself in warmth when going to bed in winter, it's better to maintain a cooler room.

"When your core temperature does not drop properly at night, your body cannot enter the deepest sleep stages that help your immune system repair itself," says Dr. Jacobs. "The result is waking up feeling drained and more likely to catch whatever bug is going around.”

A woman lies awake in bed wafting a fan in her face because she is too hit to sleep — (Image credit: Getty Images)

The perfect temperature for sleep is between 65 to 70 °F (18 to 21 °C), as this cooler feel helps your sleep cycle stay aligned with your circadian rhythms.

“If you wake up feeling hot and restless, it is a sign your bedroom might be too warm," says Martin Seeley, CEO at MattressNextDay. "Try using breathable cotton sheets and lighter layers instead of a heavy duvet."

2. Try the 15 minute method

The 15 minute sleep rule encourages you to get out of bed to help you sleep; but it's not as strange as it sounds.

Lying awake at night weakens the connection between "sleep" and "bed" in your brain (also why we don't encourage bed rotting.) You might also find the 'helpless' feeling of being unable to sleep stressful, causing your brain to associate the bed with anxiety.

However, getting out of bed once you've been lying awake for 15 minutes disrupts these associations. We recommend leaving the room and engaging in a calming activity (such as reading) until you feel ready for sleep.

For those experiencing feverish flu symptoms, this can also give your bed, and your head, a chance to cool down.

A woman wrapped in a blanket sat by a lit fireplace reading a book as the evening draws in — (Image credit: Getty Images)

3. Add 'worry time' to your day

There's no easy cure for nighttime anxiety but the constructive worry method can help those who find themselves kept awake by racing thoughts to fall asleep faster.

The method encourages taking 15 minutes every evening (not too close to bedtime) to write down three worries, followed by three solutions for you to undertake the next day. This gets the anxious thoughts out of your mind and onto the page.

4. Keep a consistent sleep schedule

Our sleep cycle is a creature of habit but over the holiday season, many of us find our consistent routine gets knocked all over the place.

Late nights, later mornings and the occasional post-lunch nap all disrupt your sleep schedule and as a result, when you finally climb into bed you might find it more difficult than usual to drift off.

A woman lifts her arm out from under her white duvet in order to turn off her alarm clock — (Image credit: Getty Images)

The best advice is to maintain consistency as much as possible, which means even after a late night, set your alarm for your usual wake-up time. You'll find it much easier to fall asleep the following night, while a mid-morning nappucino can power you through the slump.

5. Listen to your body

Christmas comes but once a year and as a result, many of us feel obliged to push through tiredness and sickness to avoid holiday FOMO.

But in the long run this is probably going to do more harm than good. Your body will struggle to keep up with your lifestyle until you're eventually forced to step back.

"If you feel a cold coming on, it’s not a sign of weakness to rest, it’s a biological signal that your immune system needs energy," explained Dr. Rubin, when advising us how to sleep for a strengthened immune system.

Rather than skipping sleep, he advises extra rest: "going to bed 30–60 minutes earlier for a few nights can make a real difference."

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Ruth is an experienced Senior Staff writer at Tom’s Guide, covering all things sleep and mattresses. She writes to help people sleep better, from how-tos to the latest deals to mattress reviews, and has interviewed an array of experts who share her passion. She is also our specialist on memory foam — she’s flown around the world to see memory foam being made — and leads our hotel mattress content. She has a deep interest in the link between sleep and health, and has tried enough mattresses, from Helix to Nectar to Simba, to know the right bed really can make a difference to your wellbeing. Before joining the team at Tom’s Guide, Ruth worked as a sleep and mattress writer for our sister website, TechRadar.

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