While it might not be immediately apparent, your body and brain work tirelessly while you rest to repair cells, process information, and remove toxins, among other tasks. It’s hard work, but that doesn’t mean you should be working up a sweat while you sleep—although many people do.

Checklist of reasons temperature rises when you sleep

Why Do I Get So Hot When I Sleep?

Your body temperature decreases before bedtime, reaching its lowest point in the sleep cycle’s initial stages, known as the non-rapid eye movement (NREM) period. Ideally, it should remain lower throughout the night to help you get the quality, restorative shuteye you need. But for many people, things don’t go so smoothly. If you’re consistently waking up overheated, uncomfortable, and drenched in sweat, one of a few factors may be to blame.

  • You’re Sharing the Bed

Sharing the bed with a partner or pet can be nice, but the extra warmth from another body may be too hot for you to handle. This doesn’t mean you have to sleep in separate beds. If your mattress is too small to provide sufficient room for both of you to sleep comfortably in your own space, simply consider going up a size.

  • Your Environment Is Too Hot

This could be Mother Nature’s fault or a product of differences in thermostat preference between you and other household members. The former is an issue during warmer months for people in most regions, but especially those in the Sun Belt, where temperatures frequently climb into the triple digits with intense humidity levels to match. Utilizing fans, turning up the air conditioner if you have one, and opening the windows at night to allow cooler air to filter in can all provide relief.

If you’re too warm because someone else in your household keeps the heat cranked up, consider investing in a smart heating and cooling system that can produce different temperatures for different rooms. If the discrepancy is with your partner, it might be harder to mitigate. Your natural internal temperature is affected by a wide range of factors, including age, weight, sex, and even activity levels. Solutions for a partner temperature mismatch can include warmer or cooler pajamas and customized pillows.

  • You Have a High Metabolism

Your metabolic rate is the speed at which your body burns through calories. This process raises your internal temperature, so those with faster metabolism often tend to be warmer. On average, many men have higher metabolic rates than women. Your metabolic rate can also shift throughout your life due to things like age or a change in activity levels. As these shifts occur, you may find your sleep temperature affected.

  • Your Hormones Are Fluctuating

Hormone fluctuations, including those related to menstruation, can cause excessive warmth too. Changes in reproductive hormones affect the hypothalamus, which controls the body’s temperature. Menopause is known to cause significant temperature changes and hot flashes. Some people also have an underactive or overactive thyroid, a gland that produces hormones and affects your metabolism. Those with thyroid issues are likely to experience significant temperature variations.

  • Your Mattress Is Trapping Heat

If you’re overheating every night, mattresses and bedding may also be part of the problem. Memory foam, in particular, tends to run hot. It is typically made from a dense, synthetic material that doesn’t absorb moisture or ventilate efficiently. The foam’s body-contouring properties, which make it excellent for support, can also trap body heat. Similarly, sheets made with synthetic materials tend to be less breathable when compared to cotton or bamboo.

Consider choosing natural-fiber sheets and a mattress made with cooling technology. Many mattress manufacturers now incorporate advanced ventilation and temperature-regulation systems to prevent overheating and promote optimal comfort.

How Do Cooling Mattresses Work?

The original memory foam mattress, devised by NASA and adapted by Swedish scientists for the public, was viscoelastic. Many companies still use this material today, but there are other foams available too.

Viscoelastic material is absorbent and soft, conforming to the sleeper’s body in response to pressure and heat. This is particularly useful for people with chronic pain or musculoskeletal conditions, because these mattresses offer support and cushioning where they’re needed most.

Painful, inflamed areas of the body tend to produce more heat due to increased blood flow. The mattress responds to this by cradling these areas to relieve pressure points and promote optimal balance. The caveat is that it also traps and collects this body heat.

Fortunately, a lot of research goes into sleep, and many innovative mattress-makers have come up with solutions to the problem of trapped heat. Some mattresses contain air pockets or channels within their layers, which promote ventilation. Others are made with unique temperature-regulating materials, either within the mattress or in the form of a cover or topper.

  • Pocket Coils- Traditional innerspring mattresses support the body using springs connected to one another in a network. Mattresses made with pocket coils, in contrast, contain individually wrapped coils that stand uniformly apart throughout. This minimizes movement throughout the bed due to position shifts and provides better support and air circulation.
  • Open-Cell Foam- Open-cell foam is a type of rubber-like material that contains tiny air channels to promote ventilation. It’s essentially traditional memory foam, with the added benefit of better air circulation.
  • Gel Foam- A type of foam that incorporates gel microbeads. The microbeads create channels similar to those in open-cell foam, but they’re a bit more high-tech, made with “phase-changing” ingredients that absorb and release body heat, rather than merely promoting ventilation.
  • Copper-Infused Foam- Copper is highly energy-conductive. It draws and absorbs excess body heat and transfers it elsewhere to produce a temperature-neutral effect. Copper is also antimicrobial and works to remove not only heat and moisture, but also bacteria and odors.

Combinations and Hybrids

Mattress companies are continually experimenting with different combinations of these materials. The resulting mattresses, called hybrids, can offer superior support and temperature regulation. Some of the top hybrid models on the market today include:

  • The DreamCloud Luxury Hybrid Mattress– The DreamCloud Luxury Hybrid Mattress was voted “Best Mattress” by Slumber Search and Non-Biased Reviews, and “Best Hybrid Mattress” by Mattress Advisor. It combines two temperature-regulating methods: pocket coils and gel foam. The individually-wrapped coils ensure even weight distribution and efficient ventilation, while the gel foam draws out and disperses body heat for ultimate comfort. The mattress contains five layers for optimal balance, support, and relief on pain and pressure points.
  • Midnight Luxe by Helix– The Midnight Luxe by Helix earned top credentials from Allure, Business Insider, Cosmopolitan, the Wall Street Journal, Apartment Therapy, GQ, and Wired Recommends in 2020. It features the same range of features as the brand’s best-selling Midnight model, with the addition of zoned lumbar support and a quilted pillow top with an Ultra-Breathable Tencel Cover for optimal temperature regulation. The coils provide enhanced airflow in addition to pressure relief, while the memory foam offers customized body-contouring comfort.

New Technology and Patents

In addition to creating combinations of existing materials, mattress manufacturers also innovate constantly to find new materials and methods that will provide sleepers with more comfortable and quality shuteye. Some keep their technologies under lock and key, while others release their proprietary products for market-wide use, like the original memory foam inventors.

  • MOLECULE 2 AirTec Mattress with Microban by MOLECULE– Microban AEGIS Microbe Shield® technology is a liquid additive mixed into Microban materials, which contains a positive charge that attracts and eliminates bacteria. This is complemented by an Antimicrobial Cover with Microban® and a one-inch layer of BioCHARGE™ crystal-embedded foam to improve circulation. These layers sit atop cooling Air-Engineered™ AirTEC™ foam which provides optimal temperature regulation and RecoveryFLO™ and ContourFLO™ layers for support and pressure relief.
  • AirFoam by Nolah Mattress– Nolah AirFoam™ is the company’s patented take on traditional memory foam. AirFoam is temperature-neutral, so it doesn’t trap heat, resulting in a cooler sleep environment. Nolah’s AirFoam mattresses also provide superior comfort by placing four times less pressure on the hips and shoulders than standard memory foam. They are designed to be more durable than memory foam and last a lifetime, so a lifetime warranty is available.
  • Health Series Refresh by Natural Form– The Health Series Refresh mattress contains the company’s patented Helix Pod Support System for superior pressure relief, as well as firmness controls that allow you to adjust the firmness level on each side of the bed. A hybrid foam topper layers over the pod system with a merino wool cover for natural temperature regulation. According to the company website, Helix also utilizes replaceable and recyclable components, making this an eco-conscious choice.

Other Options for Those Who Sleep Hot

Cooling mattress pads and toppers are designed to absorb moisture and body heat, and they work best in conjunction with a temperature-neutral bed rather than alone. If you use a cooling topper or pad on top of a standard memory foam mattress, much of your body heat may still be absorbed by the bed beneath, limiting the pad or topper’s effectiveness. Many mattresses come with mattress pads or toppers equipped with cooling technology, but you can also purchase one separately.

  • Cooling Sheets- Cooling sheets are available with some of the same cooling technologies, such as phase-changing materials, available in mattresses, toppers, and pads. Certain fabrics used in sheets, like Tencel, linen, bamboo, and cotton, are also naturally cooler and more breathable.
  • Bed Fans- Blasting the air conditioning may seem like a good way to keep cool during the night, especially in summer. However, this approach isn’t the most efficient and may end up wasting more energy than it’s worth. Enter bed fans. These devices are designed to target the bed to draw and remove heat and produce a gentle cooling effect, keeping you comfortable with much less of an effect on your power bill. Look for fans with features like automatic shut-off and energy-saving technology. Some also come with easy-access controls that let you adjust the settings remotely from your bedside table.

Stay Cool, Sleep Well

Your body temperature plays an essential role in the quality of your nightly rest, which in turn affects how you feel the next day. Investing in sleep-enhancing items like a cooling mattress and bed accessories can help you enjoy more restful nights and easier, more energized days. When shopping for any of the above items, be sure to look at customer reviews and review the company’s return policies and warranties to ensure you get the best deal for your money.