Yet, despite these efforts, many of us still find ourselves battling persistent colds, coughs, and fatigue. Why? Because we are ignoring the single most powerful, natural immunity booster available to us: Sleep.

Many people believe we sleep better in winter when, in fact, we do not. In general, the winter months are disrupted by the physiological effects of artificial heating, dry air, dietary changes, and lack of sunlight, resulting in fragmented and low-quality sleep.

India's sleep crisis is worsening, with a 2025 Resmed study showing 49% of Indians struggle to sleep multiple times a week, yet few seek help. Those seemingly innocent rituals, like binge-watching, late-night screen time are likely the main culprits and those who average six hours of sleep (or less) a night are FOUR TIMES more likely to catch a cold when exposed to the virus than individuals who sleep seven hours or more.

Sleep is not just the pause button; it is your body's garage for repairs. If you skimp on sleep, you cannot maintain your defense system. This article details the impact of cold weather on sleep, the biological connection between sleep and immunity, and how to achieve good sleep health this season.

Key Takeaways: Sleep is Your First Line of Defense

• The 4x Risk Factor: If you are not sleeping at least 6 hours you are 4 times more likely to get sick from a virus.
• Cytokines are the Key: Sleep will result in a release of cytokines, the proteins in your body that target infection and inflammation. Less sleep means fewer cytokines, which in turn results in an immune system lacking the strength to fight off infection.
• Winter is a Sleep Disruptor: Artificial heating, dry air, and heavier meals result in the body being unable to regulate its temperature and circadian rhythm (our internal clock which tells us when to sleep or wake up).
• Vaccine Efficacy: Sleep is imperative to getting the most from your flu shot. Your body must rest in order to create antibodies that the vaccine is asking your body to create.
• The Solution: Good sleep hygiene is to keep your room cool, humidified, gain sunlight in the morning, and follow a routine.

The Science: How Sleep Acts as an Immunity Booster

If you want to understand why lack of sleep makes you sick, you have to look at what happens on a cellular level after your eyes are closed. Sleep is an active immunological state. The first item to note today is the release of cytokines.

1. The Cytokine Connection: Once you enter the deep stages of sleep (often referred to as Slow Wave Sleep), certain proteins in your immune system are released called cytokines.

• The Role: Some of these proteins are specifically intended to promote sleep. Other cytokines are essential to fighting infection and inflammation.
• The Deficit: Now, if you wake up cold and thirsty and/or you haven’t had enough time to sleep, your body will not produce enough of these protective proteins because of your lack of sleep. If your body does not have this "army" of proteins, it may not be able to effectively fight against the viruses and bacteria with which we are in contact, if and when we sleep.

2. T-Cells: The sticky warriors. T-cells are another part of your immune response and defend against viruses. I use the term sticky, because T-cells are white blood cells that depend on the ability to identify virus (infected) cells (flu cells, for example) and destroy the cell.

• The Research: A study published in the Journal of Experimental Medicine found that sleep improves T-cell "stickiness."
• When the study subjects had disrupted sleep, their T-cells became less "sticky."

3.  The "Fever" Response

Have you ever noticed you get a fever at night? That's because the immune response works harder when you sleep. Sleep conserves energy that the body redirects towards the immune system. If you don't sleep, you are robbing your immune system of the energy it needs to mount a fever response and burn out the infection.

The "Why": What Causes Poor Sleep in Winter?

If sleep is so cozy, why do we struggle with it in November and December? The causes are often environmental and behavioral.

1.  The Overheating Trap (Thermoregulation)

This is the most frequent error. We link winter with comfort, so we cover our bodies with thick blankets, wear heavy socks, and turn on the room heater.

• The issue is that in order to fall asleep and stay asleep, your core temperature actually needs to be reduced by 1-2 degrees Fahrenheit.
• The outcome is that if your room is hot or your bedding is heavy, your body does not have the capability to cool itself. This stops you from getting into deep and restorative sleep, meaning you constantly wake up sweaty and uncomfortable

2.  The Dry Air (Humidity)

The air in winter is inherently dry to begin with, but you can easily make your bedroom feel like a desert with an electric heater or blower (less than 30% humidity).

• Problem: Dry air dries out your nasal passages and throat.
• Result: You wake up with a dry mouth, scratchy throat, or headache. Additionally, it increases snoring and can trigger asthma or allergy flare-ups, which impact your sleep quality.

3.  Winter Blues (Circadian Rhythm Disruption)

The days are shorter and the nights are longer and we have very little exposure to natural sunlight compared to other months.

• Problem: The primary cue that tells your body when to be alert and when to produce melatonin (the sleep hormone), is the sun.
• Result: When you don’t get sunlight in the morning, you can feel groggy in the day and ‘wired’ at night. This can also lead to Seasonal Affective Disorder (SAD), which has a strong association with sleep issues like hypersomnia (oversleeping and feeling unrested).

4.  Comfort Food Coma (Diet)

During the winter season, there is a biological urge to consume more food — especially calorie-dense, heavy comfort foods (for example, gajar ka halwa or rich curries).

• The problem is that the consumption of heavy, spicy, or fatty foods close to bedtime puts excess stress on the digestive system.
• As a result, you may experience indigestion, acid reflux (GERD), and erratic blood sugar levels at night. These physical conditions can cause you to wake from sleep.

5 Essential Tips for Good Sleep Health This Winter

You don't need medication to improve your sleep; you just need to enhance your surroundings and routines. Here is your winter sleep kit.

1.  Get the "Goldilocks" Temperature Right

Stop keeping your room too hot.

• The Tip: For adults, the perfect temperature for sleep is unexpectedly cool. Between 65°F-72°F (18°C - 22°C) is ideal.
• The Strategy: Rather than using your heater all night, use a hot water bottle to pre-warm the bed (up to the point you crawl in), then remove it or simply turn it off. Also, put on clothing made from breathable layers like cotton, not heavy wool, permitting your body to internally stabilize temperature.

2.  Humidify Your Habitat

You have to find a way to counteract and minimize dry air to reduce the chances of that "dry throat" wake up call.

• The Tip: You can expect a relative humidity level in your room to be between 40% and 50% okay.
• The Strategy: When you wake up due to dry air blowing at you, you can use a cool-mist humidifier near your bed room space. If you don't have a humidifier, an easy low-tech way to add moisture back to the environment is to leave a bowl of water near your heater or radiator.

3.  Morning Light Prescription

You should set your body clock.

• The Tip: Get a minimum of 15-20 minutes of natural morning sunlight.
• The Strategy: Sit on the balcony or near a window to enjoy your morning cup of tea/coffee. This warmth when exposed to light will help to inhibit the release of melatonin, increases your mood and starts a timer (12-14 hours) for your brain to release melatonin, so you can fall asleep faster at night.

4.  Make a "Tech-Free" Wind Down

While we have talked about how screens cause "Digital Burnout", they can also cause you to lose immunity by taking your sleep.

• The Tip: Blue light inhibits melatonin.
• The Strategy: Stop using devices one hour before bedtime. Rather, make this your winter ritual: Enjoy a warm (not hot) bath, read a physical book, or practice some gentle stretching. This will let your body know it is safe now to shut down.

5.  Watch the "Nightcaps"

Many people drink alcohol in winter to feel "warm" or sleepy.

• The Problem: While alcohol acts as a sedative and helps you fall asleep faster, it destroys the quality of your sleep. It blocks REM sleep (the dreaming stage) and causes you to wake up frequently in the second half of the night as it metabolizes.
• The Strategy: Limit alcohol intake and stop drinking at least 3 hours before bedtime. Swap the nightcap for warm milk with turmeric (haldi doodh) or chamomile tea.

When Poor Sleep is a Medical Disorder

Occasionally, no matter how correctly we do things, we cannot sleep. If you experience any of the following, it might be more than just "winter insomnia":

• Loud snoring, or gasping for air while sleeping (Signs of Sleep Apnea).
• Taking longer than 30 minutes to fall asleep - repeatedly.
• Waking up early and cannot return to sleep.
• Feeling tired during the day regardless of getting "7 or 8 hours" of sleep.
• Restless legs or jerking limbs.

These are symptoms of clinical sleep disorders that require medical attention.

Expert Care at the SGRH Centre for Sleep Disorders

Sleep isn't a luxury, it's life. This biological need is especially critical during the peak viral season. If you're struggling, The Department of Sleep Medicine at Sir Ganga Ram Hospital offers advanced help for the entire spectrum of sleep problems, from assessment to treatment.

With comprehensive Sleep Studies (Polysomnogram) to expert management of Insomnia and Obstructive Sleep Apnea (OSA), our multi-disciplinary team is here to unearth the source of your fatigue. We won't just get you sleeping. We will help you build your body's natural defence system.

Don't let broken and dysfunctional sleep expose you this winter. [Book an appointment with SGRH today!]

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