Graph showing optimal sleep temperatures with a backdrop of cold, warm, and hot zones, held by a hand to symbolise personal control over sleep environment.

Your bedroom temperature is a major factor in the quality of your sleep. If it is too hot or too cold, you are likely to wake up more often. We’ve put together a guide to help you balance your bedroom temperature with your core body temperature and to explain why sleeping in natural bedding will also help.

Does your body temperature change when you sleep?

Your body temperature will fluctuate throughout the day and whilst you sleep. Our body temperature is closely tied to biological processes that follow our 24-hour internal clock in our brain that regulates cycles of alertness and sleepiness, based on exposure to light and darkness. This is known as circadian rhythm, and this also guides other bodily functions such as appetite and hormone production. Healthy sleep goes through four stages, the first three of which are known as non-rapid eye movement sleep. During the second of these stages, your body begins to slow down for deep sleep. Your core temperature drops, heartbeat and breathing levels decrease and eye movements stop, and this process continues into the third stage, which is characterised by deep or ‘slow wave’ sleep.

After about 90 minutes of sleep, your body temperature then increases as it enters the fourth stage, known as REM (rapid eye movement) sleep, along with heart rate and blood pressure. By the time this stage concludes, these functions will have reached near waking levels, but then the sleep cycle begins again, and your body temperature will decline once again. Healthy sleep means longer REM stages during the sleep cycles as the night progresses.

How do heat and cold affect sleep?

Both heat and cold exposure during sleep can cause you to wake up more during the night. Too much heat may also cause a decrease in the deep sleep and REM stages of your sleep cycle – and mostly during the first cycle of the night. Your body will struggle to acclimatise to sleeping in heat, even after several nights of exposure. High humidity levels can compound this. Exposure to cold tends to impact mainly on sleep later in the night, when the REM cycles are longer. Sleep researchers have also noticed that cold exposure can affect cardiovascular activity and elevate the morning blood pressure surge.

How can I achieve the best sleeping temperature?

Sleep experts suggest that an air temperature between 16c – 18c is optimal for sleeping, and here are some steps you can take to maintain your core body temperature throughout sleep.

  • Setting your bedroom thermostat: Many of us may have heating on in the bedroom for an hour in the evening but set it to switch off before bedtime. Most well insulated properties will not lose too much warmth overnight. If, however, you have an older, less well insulated property that loses a lot of heat overnight, then you may prefer to set the thermostat on a ‘tick over’ temperature of 16c. If you find yourself feeling too hot or cold, then adjust the thermostat to reach your ideal temperature.
  • Keep the bedroom well ventilated: Natural ventilation has been linked to better sleep quality, particularly during the transitions between seasons, and in parts of the UK with milder climates. Unless it is especially cold, having a window open, even slightly, will promote better sleep.
  • Take an evening shower or bath: Showering or bathing in warm water an hour or so before bed will then generate a cooling effect afterwards and this will help trigger your body into sleep mode.
  • Choose PJs or other sleepwear made from natural materials: Natural materials are breathable and temperature regulating. Synthetic fibres will trap heat, which may sound great in the cooler months, but it also means you could overheat, and this will wake you up. Opt for 100% cotton or even wool sleepwear. One recent study showed that people were likely to fall asleep faster whilst wearing wool bed clothes.
  • Opt for natural bedding and bedlinen: The same rule applies with bedding as with sleepwear made with natural fibres. Duvets made with synthetic fibres tend not to be temperature regulating, and feather/down duvets generally just insulate, whereas duvets made with 100% natural wool encased in 100% cotton are breathable and will work with the ambient temperature of your bedroom and your core body temperature to keep it balanced throughout the night. The wool will react with any changes and help you to sleep more peacefully. With a warmer weight wool duvet, this means that even if you prefer to sleep in a cool bedroom, the wool in the duvet will still keep you warm but still be able to release heat if required.

A lightweight wool duvet will work effectively in the warmer months as it will release heat if your core body temperature starts to rise. It’s also a good choice if you are someone who experiences temperature fluctuations or hot flushes. If you want to know how tog factors work for wool duvets, then you’ll find more information here. Wool is also dust mite resistant so is ideal for those who suffer from allergies associated with dust mites. Also make sure to choose 100% cotton or linen sheets and duvet covers as this will ensure the wool is able to do its temperature regulating work.

  • Block out sunlight: During hot weather, closing your bedroom blinds or curtains can help to keep rooms cooler. It can also help to keep your bedroom warmer when it’s cold outside.

At Devon Duvets, we’re experts at making wool bedding, and have been doing this for over 15 years. Our luxurious duvets are individually handcrafted by our team of seamstresses in our workshops on the edge of Dartmoor. Natural, sustainable, and chemical free, we use fully traceable British wool from selected farmers across Devon and the Southwest, encased in beautiful 260 thread count cotton casing, made from cotton fibres certified by Better Cotton. Each duvet is stitched to a design that we created with a special drape to ease you into peaceful slumber.

If you have any questions about our range of natural soft filled bedding, then please contact team by calling 01752 345399 or via email.