This is the Ideal Bedroom Temperature to Avoid ‘Junk Sleep’

Millions of people across the UK could be at heightened risk of poor sleep as the country moves into spring, with longer days, lighter evenings, and changing temperatures disrupting established sleep routines.

According to research by Mental Health UK, one in five UK adults say they do not get enough sleep, while research from The Sleep Charity shows that more than two-thirds of Brits experience sleep problems and have yet to seek professional support, often living with the issue for over six years.

This suggests that around 10.8 million UK adults are struggling with poor sleep, with experts urging Brits to adjust their habits and bedroom environments to avoid slipping into what’s known as “junk sleep”: spending sufficient time in bed, but missing out on the restorative deep and REM sleep the body needs to properly recover.

To mark Sleep Day, Sam Carter, Radiator Expert at Appliances Direct and Samantha Sadighi, Certified Sleep Practitioner and Founder at Easy Sleep Solutions, share expert insight into why sleep quality matters and how bedroom temperature plays a critical role.

Samantha Sadighi, Certified Sleep Practitioner at Easy Sleep Solutions, told Appliances Direct,

Why is sleep quality just as important as sleep duration?

“You can spend 9 hours in bed, but if it's 'junk sleep' (fragmented and shallow), you won't reap the benefits.

“Physical restoration, growth hormone release and tissue repair happen mainly during deep sleep, while memory consolidation occurs during REM sleep. 

“Without quality sleep, the duration is just an empty number.  It's very much about quality over quantity.”

What happens after just one poor night’s sleep?

“Missing out on quality sleep for even one night leads to:

• “Emotional Volatility: Increased irritability and reduced patience.
• “Cognitive Fog: Slower reaction times and poor executive function (deciding, planning).
• “Lapses in Focus: In the case of severe sleep deprivation, individuals might encounter 'Micro-sleeps' or a general inability to sustain attention.”

“In the long term, chronic sleep deprivation is a systemic stressor linked to:

• “Cardiovascular Disease: Higher blood pressure and increased inflammation.
• “Metabolic Issues: Increased risk of Type 2 diabetes and obesity (due to disrupted leptin/ghrelin levels).
• “Neurodegenerative Decline: Reduced clearance of metabolic waste (like beta-amyloid) from the brain.

“Not getting enough sleep doesn't guarantee that you will suffer with any of the above, but it does increase your chances.”

What is the ideal bedroom temperature for sleep, and why does it matter?

“The sweet spot for most adults is roughly 16–18°C. For babies, the NHS usually recommends 16–20°C.

“This range facilitates the heat loss required to initiate sleep. A cool room acts as a thermal sink, drawing heat away from your skin to help lower your core body temperature in preparation for sleep.”

Why does the body’s core temperature drop at night?

“Our body operates on a circadian rhythm (aka body clock) where core temperature peaks in the late afternoon and begins to drop about two hours before bedtime.

“Blood vessels in the hands and feet dilate (vasodilation) to radiate heat away from the core.

“If we're really cold and our hands or feet are chilly, then our bodies cleverly try to keep the heat in our core, which is why bed socks can often be a good idea, as they help to 'suck' the warmth from our core and evenly distribute it to our peripheries instead.

“If a room is too warm, the body cannot shed that heat efficiently, stalling the biological 'green light’ for sleep.”

How does sleeping in a room that’s too warm affect falling asleep and staying asleep?

“A room that is too warm is generally more disruptive than one that is slightly too cool.

“It delays sleep onset because the brain is busy trying to thermoregulate rather than transitioning into sleep states.

“It leads to increased wakefulness and restlessness as the body struggles to maintain its lower nocturnal temperature, and confuses our brain and body as it's not what it is expecting.”

Is being too cold just as bad as being too hot?

“While less likely to disrupt sleep stages than heat, extreme cold can make it hard to fall asleep due to physical discomfort or shivering. However, once asleep, the body is generally better at tolerating cold (with blankets) than heat. It's often a good idea to layer bedding when it's particularly cold, so it's easy to increase or decrease our comfort more easily.

“Overheating actively interferes with the act of falling asleep, whereas being too cold is really more about comfort.”

How do poor temperatures disrupt deep sleep and REM sleep?

“Even if you don't 'wake up', poor temperatures fragment your sleep architecture.

“Deep sleep is the body’s most restorative phase. Heat can cause 'micro-arousals' (mini-awakenings that we're not consciously aware of), pushing you back into lighter sleep stages.

“During REM sleep, our internal thermoregulation almost shuts down. If your room is too hot or cold, the brain may wake you up to "fix" the temperature, significantly reducing your total REM time.

“Ideally, we want a fairly even mix of both Deep and REM sleep. We generally have more deep sleep earlier in the night, and then the balance changes, and we have more REM in the second half of the night. Both are important.”

Sam Carter’s 8 expert tips for setting the right bedroom temperature

Radiator and heating expert Sam Carter shares his advice:

1. Manually turn radiators down before bed: Turn bedroom radiators down in the evening, because bedrooms need to be cooler than living spaces once you’re preparing for sleep. A temperature that feels comfortable when active often becomes too warm once you’re under bedding.  
2. Use zonal heating: Avoid heating the whole house to evening comfort levels and then leaving bedrooms unchanged overnight. Bedrooms should be treated as their own temperature zone. You could use smart valves or thermostats to help schedule heating around your routine.  
3. Gradually reduce temperatures: Aim for around 16-18°C in adult bedrooms by reducing radiator output gradually rather than switching heating off completely. A slower reduction allows the room to cool naturally.  
4. Try thermostatic radiator valves: Use thermostatic radiator valves to control bedroom temperatures independently from the rest of the house. This allows living areas to remain comfortable while bedrooms cool down.  
5. Avoid overnight heating during warmer months: Running bedroom radiators overnight is rarely necessary, particularly when sleeping under a duvet or layered bedding. Overnight heating often pushes bedroom temperatures higher than needed.  
6. Don’t block radiators with furniture: Keep beds positioned away from radiators, as direct heat can create localised hot spots. These often cause overheating even when the overall room temperature is reasonable.  
7. Add layers to your bedding: Layer bedding instead of turning the heating up, allowing comfort to be adjusted during the night without overheating the room.  
8. Use curtains and blinds to support room heating: Close curtains or blinds in the early evening to retain warmth, then reduce heating before bed so trapped heat does not continue to build up overnight.

For further home heating, radiator, and air conditioning products to help you get a better night’s sleep, visit https://www.appliancesdirect.co.uk/c/heating-and-air-conditioning.