What Not To Sleep In If You Have Night Sweats

by Catherine Rust on September 22, 2021

Ah, night sweats – or, hot flashes at night, if you prefer. They are hot flashes’ evil twin. Chronic night sweats will have you waking up cold and clammy and sleep deprived.

But, did you know that what you wear to bed can make them worse? Really! It has to do with how fabric reacts to the heat and sweat produced by your body during a hot flash…

There is a lot of misinformation about which fabrics are best for sweaty people. Many are promoted as being great wicking fabrics. The thing is that what works during the day may not work as well at night.

Why? Because at night you have extra layers of covers between you and the outside world. 

Those covers act like insulation, just like the insulation around a house. Your sleepwear and covers keep you warm and protected from the outside elements. But just like a home’s insulation, they can trap any heat and sweat your body produces underneath those covers keeping it next to your body.

Your sleepwear is your first line of management against the sweat and heat you produce. If your sleepwear is made from wrong materials, it will make you damp and hot, and when you wake up you'll be soaked.

Here are some of the worst fabrics you can sleep in.

Polyester

There are a lot of sleepwear garments made of polyester because it is an inexpensive fabric. It is, however, synthetic, (petroleum-based) and doesn't respond to heat and moisture changes produced by your body. 

For you that means that heat and moisture will be trapped next to your body, and you will remain hot and clammy, waking up to flip covers with each night sweat.

Cotton

You’re probably surprised by the fact that cotton is a terrible fabric for people with night sweats. For one thing, it’s a natural fabric that’s very breathable. Many cotton fabric weaves will support wicking heat away from your body. But there’s a catch: cotton loves water. It is reluctant to give up any water it comes into contact with – that’s why towels are made of cotton.

That means all that sweat your body has produced to cool you down is now trapped in your cotton sleepwear next to your skin. You covers are also preventing the moisture from going anywhere too.

In the outdoor community they have a saying: “Cotton is rotten.” As you heat up and cool down, cotton will cling to you and you will become chilled and wet.

Silk

Silk is a wonderful insulator. About 30 years ago, maybe more (am I showing my age??), silk was introduced into long underwear. It helps insulate you against the elements. I am going to keep drawing on the house analogy so forgive me – An insulation’s function is to protect all things inside from the exterior elements, whether it is too hot or too cold. On the inside, the assumption is that there is a constant temperature ruled by a well-functioning thermostat.

In a body with night sweats, the internal thermostat is broken. Heat is thrown off at any time because the signal is sent that your core needs cooling down. If all that heat and moisture is given off inside a well-insulated place, the place will heat up. In a house, you open windows. When you’re sleeping you have to throw off covers. Silk is also terrible at managing moisture. If you have a silk blouse or camisole or some nice lingerie, think about what happens to it when you sweat.

Wool

Like silk, wool is a great insulator. But unlike silk, it is wonderful at managing moisture. In fact, in homes, wool is becoming a popular choice for insulation because it works well even when wet. So, you would think that it would be great for night sweats.

The problem with wool is that even though it manages moisture really well, keeping you dry, it also keeps all the heat that you generate next to your body. You wake up and have to cover-flip because you’re so hot.

So, if these are fabrics you shouldn’t wear to bed if you have night sweats, which fabrics are okay to wear to bed for night sweats?

What are we looking for in acceptable fabrics?

In order to manage night sweats well, we ideally want a fabric that can absorb and wick moisture as quickly as possible. In fact, we want it to manage moisture so quickly that you, the sleeper, avoid being disturbed. That means the fabric needs to respond to heat and moisture actively. Not all fabrics can do that effectively, as we’ve seen. But there are a few that do.

Viscose and rayon (acceptable-ish)

Viscose and rayon are two sides of the same coin. They are both cellulose-based semi-synthetic fabrics. What that means is that the substrate, or first ingredient of the fabric, is some sort of wood or grass-based, cellulosic material. The most common cellulose material used is a fast-growing deciduous tree such as birch or beech. Other common cellulose materials are bamboo, eucalyptus, and hemp. These materials are turned into pulp and chemicals are added. Then the mixture is extruded through spinarets and woven together to create rayon or viscose fabric.

In terms of whether or not rayon cools your sweats and manages moisture, it is a breathable fabric and will wick sweat away from you. It has medium heat managing ability, however, and is not as effective as some other fabrics.

Finally, rayon and viscose tend to be more delicate than other choices (see below). Most rayon and viscose sleepwear won’t last very long and are not easily repairable. From a cost perspective, however, they tend to be reasonably priced, making them a good choice for those on a budget.

The best fabrics for people with night sweats

You might be wondering what on earth you can wear to bed if you have night sweats if you don’t like to sleep in the nude (and most people don’t). There are some great fabrics for managing night sweats. They are fast-wicking and manage heat (thermoregulate) so you sleep with a more even temperature throughout the night. That means you wake up less, if at all, and sleep dry and comfortable all night long. The best fabrics have some similar characteristics: they all respond to heat and moisture actively due to their fibre structure and they are all durable so they last a long time.

Linen

Linen is an age-old “workhorse” fabric that not only wicks moisture and manages heat, but is also incredibly strong so it lasts a very long time. A well-made linen garment will last for decades and the longer you wear it, the softer it becomes. The fibre structure is hollow and can wick heat and sweat away from your body quickly, so you stay dry and comfortable and wake up less often. A few drawbacks of linen are that it is not stretchy, it takes a while for high-quality linen to soften, and the upfront cost can be expensive.

Lyocell

Like rayon and viscose, lyocell is a semi-synthetic, cellulose-based fabric. However, unlike rayon and viscose, lyocell uses fewer chemicals that are also less harmful on the environment. Further, the fabric processing itself keeps much of the cellulose-based product intact so that the wearer benefits from the cellulose base’s natural properties. For example, bamboo rayon behaves like any other rayon, whereas bamboo lyocell responds to heat and moisture like bamboo would, actively managing heat and moisture to keep you dry. Some drawbacks to lyocell it is expensive, and it can be difficult to find sleepwear made from it.

Hemp

Hemp is similar in texture and properties to linen. It is very strong and, like linen, hemp-based garments can last for decades. If it is processed to be an all-natural product (and not a rayon-based product) it will retain all of its great heat and moisture managing properties. Because it is so strong, it’s best when combined with other fibres such as cotton or lyocell which will make it soft and supple. We make our sleepwear out of hemp and cotton, and it has allowed many of our clients to sleep through the night again.

If you suffer from hot flashes at night, choosing the right sleepwear will actually help you sleep more comfortably and may even let you sleep through the night again.

Check out our Simone nightgown now.

2 comments
by Catherine Rust on October 13, 2021

Hi Patricia,
Good question! Aside from our website where you’ll get a comfy, heat and sweat moderating nightgown, ;) you will have to look at the fabric tags of sleepwear to figure out whether the sleepwear is made of hemp, linen, or lyocell. If it says “bamboo rayon” it’s really just rayon and you’re better off buying a regular rayon garment without paying the premium for bamboo.

by Patricia Bilotti on October 12, 2021

Where can I purchase the right clothing to help night sweats during sleep

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