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What Happens When You Sweat at Night

March 2021 | 5 minute read

Clean beauty industry maven Mary Futher founded kaia naturals® after spending 20 years working for global beauty companies. Mary now shares her weekly content series, delivering a quick fix, home remedy, or clean beauty product suggestion for a variety of human discomforts that some may find too embarrassing to discuss.
Sweat at Night

In this week’s column we are taking a deep dive into sweating at night and how that could be responsible for your filthy pillow! Going beyond the surface and uncovering what lives in your pillow when you sweat at night, I will share how often we should repurchase and clean our pillow and a few tips to help avoid a pillow full of who-knows-what. 

Do You Sweat At Night?

Sweating at night is quite common. One study found that out of 2000 patients, 41% suffered from excess sweating at night. Here are three factors that may be triggering this nightly perspiration.   

1. Environment  
When the environment temperature rises above 85-degrees Fahrenheit (around 30-degrees Celsius), the average person could lose about two liters of sweat over an eight-hour night sleep. 

2. Hormones  
When on your period, it is common to have increased sweat levels. Changes in estrogen and progesterone levels are common PMS symptoms that lead to hot flashes and heavy sweating at night.  

3. Clothing  
Common sleepwear materials are wool, fleece and flannel however these materials can lead to overheating and a high production of sweat. I recommend natural fabrics such as, cotton or bamboo as they allow the skin to breathe, reducing the chances of overheating.

So, What's Really Living Inside Your Pillow?

When was the last time you cleaned your pillow? No, not your pillowcase – your pillow! A study done by the University of Manchester discovered the average pillow contains around one million fungal spores! These pillows that were tested were only one to two years old. Can you image what’s living in your favorite pillow that you’ve had forever?  

To get more specific, your pillow does contain a lot of bacteria. This includes bacteria from your own sweat and drool, leftover product from your hair and skin, thousands of dead skin cells and skin flakes, fungi, dust mites and dust mite feces. Not only is this unhygienic to be sleeping in, if these particles are left for too long they can lead to allergy-like symptoms like itchy eyes or stuffed sinuses.

How Much Do You Sweat At Night?

Night sweats are very common and are often led on by stress. The average person sweats out about 200 mL per eight hours of sleep. Due to high stress levels in your everyday life, you may actually sweat up to 30 times more than you normally would during a calm resting state.  

This sweat can travel through your hair as you sleep and spread oils and dirt through your scalp, making hair look oily by morning. Sweaty scalps are a warm, moist area where dandruff-causing fungus can grow and be absorbed by your pillow. 

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How To Prolong Your Pillow

At most I would only recommend using the same pillow for two years before investing in a new one. However, there are a few things I can suggest to help prolong your pillow’s life.  

Wash your pillowcase often 
I would suggest washing your pillowcase every few days as a study has shown the average pillowcase has over 17 thousand times the number of bacteria as a toilet seat after one week! 

Use a dry shampoo at night   
If you use natural products, especially in your hair, there is less of a chance of these products transferring into your pillow and creating high levels of bacteria faster. I developed the takesumi detox overnight dry shampoo as I wanted a natural product that would not buildup on my pillowcase, but still perform well on my hair. A bonus of using dry shampoo before bed is that it will help absorb hair and scalp oils from transferring onto your pillow.  

Wash and fully dry your pillow 
I recommend washing your pillow as often as your sheets. Most pillows have washing instructions written on the side tag, so be sure to check what your pillow calls for. However, a deep wash would typically include spot cleaning any stains with your favorite stain remover and throwing the pillow into your laundry machine afterwards. The most important step is fully drying the pillow, airdrying or machine drying, as you need to ensure that there is no moisture remaining in the pillow that could lead to more bacteria growth.

Is It Time to Replace Your Pillow?

Nightly sweating can cause significant damage to your pillow, not just the pillowcase. If you are considering replacing your pillow there are a few signs you should look for.  

Is there an odor? 
If you notice an unpleasant stench coming from your pillow, this is a clear sign it is filled with bacteria. I say skip the washing machine and treat yourself to a new pillow. I recommend memory foam pillows as they are durable and last much longer than generic pillows.  

What does it look like? 
Check if your pillow’s shape has changed. If it has, this is a good indicator that sweat and bacteria have found a home in your pillow.  

Are you waking up uncomfortable?  
If you wake up with a stuffy nose and red itchy eyes, your pillow may be filled with dust mites and bacteria that are triggering your allergies.  

What color is your pillow?  
If your pillow has changed from white, to off-white, to yellow, that is due to sweat, drool and oils from your hair. To reduce discoloration on your pillow use a natural dry shampoo to stop the spread of oil from scalp to pillow

Pillow Talk

If what I’ve noted so far hasn’t given you that extra push to either clean or replace your pillow, I don’t know what will!   

Knowing how sweating at night can contribute to an unhygienic sleep environment and being armed with the tools I’ve shared on prolonging your pillow’s life will have you worrying less about bacteria and experience more nights of restful slumbers.  


the takesumi detox | overnight dry shampoo

Powered by detoxifying activated charcoal and a blend of ultra-micronized powders, this dry shampoo works to absorb odor and oil while instantly refreshing hair and adding volume to all hair types. 

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