We often obsess over the firmness of our mattress or the thread count of our sheets, yet we frequently overlook one of the most critical factors in achieving a restful night: the temperature of the room. If you have ever tossed and turned on a humid summer night or shivered through a drafty winter evening, you already know that thermal comfort is essential for quality rest.
Sleep hygiene refers to the habits and environmental factors that can be adjusted to help you have a good night’s sleep. While consistency in bedtime and reducing screen time are vital, creating the correct thermal environment is equally important. In this guide, we will explore the science behind body temperature and sleep, the ideal range for your thermostat, and practical steps to improve your sleep quality tonight.
The Science: How Temperature Affects Your Body Clock
To understand why the room feels too hot or too cold, we must first look at how the human body functions. Your internal body clock, known as the circadian rhythm, regulates sleep-wake cycles. A key part of this process involves thermoregulation—the body’s ability to maintain its core temperature.
As bedtime approaches, your body naturally begins to cool down. This drop in core body temperature acts as a biological signal, telling your brain that it is time to sleep. This process is often aided by the release of melatonin, the sleep hormone. According to research highlighted by the National Library of Medicine, a lower core temperature is necessary to initiate sleep and transition into the deeper stages of rest.
If your bedroom is too warm, it can interfere with this natural cooling process, leading to restlessness and wakefulness. Conversely, if the room is freezing, your body must expend energy to stay warm, which keeps you alert and prevents you from drifting off.
What Is the Ideal Temperature for Sleep?
While personal preference plays a role, the consensus among sleep experts is surprisingly cool. For most adults, the ideal bedroom temperature falls between 16°C and 18°C (60°F to 65°F).
This range might sound chilly to some, especially during a British winter, but it is the “Goldilocks zone” for supporting your body’s natural thermoregulation. The Sleep Charity confirms that a cooler room mimics the body’s internal temperature drop, promoting deeper sleep.
Exceptions to the Rule
While 16–18°C is standard for adults, vulnerable groups have different requirements:
- Infants and Babies: Babies cannot regulate their body temperature as effectively as adults. The Lullaby Trust recommends a room temperature of 16–20°C to reduce the risk of Sudden Infant Death Syndrome (SIDS).
- The Elderly: Older adults may naturally feel the cold more acutely due to slower metabolic rates. Age UK suggests keeping the bedroom at a minimum of 18°C to prevent health complications during winter.
The Risks of Sleeping in a Hot Room
Sleeping in a room that is too hot (generally above 24°C) is one of the most common disruptors of Rapid Eye Movement (REM) sleep. REM sleep is the stage associated with dreaming and cognitive restoration. When your body overheats, you are more likely to wake up, resulting in fragmented sleep.
Common symptoms of an overheated sleep environment include:
- Night Sweats: Waking up damp or sticky is a clear sign your environment is not optimised. If this persists despite a cool room, you may need to read about causes of night sweats.
- Restlessness: The inability to find a comfortable position often stems from the body trying to dissipate heat.
- Dehydration: Excessive sweating can lead to waking up with a dry mouth or headache.
During a heatwave, the Met Office advises keeping curtains closed during the day to stop the sun from heating up the room before you even get into bed.
The Risks of Sleeping in a Cold Room
While a cool room is beneficial, a cold room (below 12°C) can be detrimental. If the air is frigid, your body activates defence mechanisms like shivering to generate heat. This increases your heart rate and alertness, making it nearly impossible to fall asleep.
Furthermore, breathing in very cold air can irritate the airways, which is particularly problematic for those with asthma or respiratory issues. If you struggle with breathing at night, you might want to explore sleep apnoea symptoms or consult a GP.
Optimising Your Bedding and Pyjamas
Your room temperature is only half the battle; what you wear and what you sleep under acts as a micro-climate for your body. This is where the concept of “tog rating” becomes essential for UK sleepers.
Choosing the Right Duvet
The tog rating measures the thermal resistance of a duvet.
- Summer (4.5 tog or lower): Lightweight and breathable.
- Spring/Autumn (7.5 to 10.5 tog): A balanced weight for variable weather.
- Winter (13.5 tog or higher): Thick insulation for cold nights.
If you share a bed with a partner who runs at a different temperature, you might consider separate duvets or a cooling mattress topper to regulate individual comfort.
Fabric Choices
Natural fibres are superior for sleep hygiene. Synthetic materials like polyester can trap heat and moisture against the skin. Instead, prioritise:
- Cotton: Breathable and absorbent.
- Bamboo: Excellent for moisture-wicking and temperature control.
- Wool: Naturally regulates temperature, keeping you warm in winter and cool in summer.
For more on selecting the right materials, see our guide on bamboo vs cotton sheets.
Practical Tips for a Cooler Sleep Environment
If you find yourself overheating, try these evidence-based strategies to lower your temperature:
1. Ventilation
Airflow is crucial. If it is safe and quiet enough, keep a window slightly open. This reduces carbon dioxide build-up and keeps the air fresh. According to the World Health Organization, good ventilation is key to a healthy indoor environment.
2. The Warm Bath Effect
It sounds counterintuitive, but taking a warm bath or shower 1-2 hours before bed can help you cool down. The warm water causes vasodilation (widening of blood vessels) in your hands and feet. When you step out of the bath, your body dumps heat efficiently, causing a rapid drop in core temperature that signals sleepiness. You can incorporate this into your evening routine.
3. Manage Light and Electronics
Electronics generate heat and, more importantly, emit blue light that suppresses melatonin. Keep your room dark and cool. If you live in a city with light pollution, blackout curtains can help maintain a lower temperature and darkness. Learn more about blue light and sleep.
Practical Tips for Warming Up Safely
If you are prone to feeling the chill, avoid cranking up the central heating, which can dry out the air and your mucous membranes. Instead:
- Wear Socks: Warming your feet causes blood vessels to dilate, which helps redistribute heat throughout the body and tells the brain it is time to sleep.
- Hot Water Bottles: Place a hot water bottle in your bed 15 minutes before you get in, but remove it before sleeping to avoid overheating or burns.
- Layering: Use layers of blankets rather than one thick duvet. This allows you to remove a layer easily during the night without waking fully.
For those with circulation issues, you may wish to read about sleep tips for poor circulation.
When Temperature Issues Signal a Health Problem
Sometimes, feeling too hot or too cold is not about the room, but about your body. Conditions such as hyperthyroidism, menopause, or infections can cause temperature dysregulation. The NHS advises seeing a GP if you experience regular night sweats accompanied by weight loss or fever.
Additionally, high stress levels can trigger a physical “fight or flight” response, raising your body temperature. Incorporating meditation for sleep or other relaxation techniques can help lower your physiological arousal before bed.
The Bottom Line
Sleep hygiene is about more than just going to bed on time; it is about curating an environment that respects your biology. Maintaining a bedroom temperature between 16°C and 18°C is one of the simplest yet most effective changes you can make to improve your sleep quality.
By investing in breathable bedding, managing airflow, and listening to your body’s cues, you can create a sanctuary that encourages deep, restorative rest. Remember, a cool room equals a sound sleep.
If you continue to struggle despite optimising your environment, consider keeping a sleep diary to track patterns and discuss them with a healthcare professional.
