A common night-time error can give people nightmares, experts say.
Sleep counsellors claim the temperature of your bedroom must be between 16 and 18 degrees if you are to get a good night’s sleep.
An overly hot room puts you at risk of suffering from feverish night terrors, according to Dr Neil Stanley, a former chairman of the British Sleep Society.
Keeping your bedroom at the right temperature will also help to prevent snoring and other disorders like sleep apnoea, Dr Stanley said.
Experts warn temperature control will prove difficult this month, as spring temperatures fluctuate wildly between hot and cold, Liverpool Echo reports.
Dr Stanley said: “In order for us to get a good night’s sleep, we need to lose around 1ºc of our internal body temperature, which sits at around 37ºc.
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“We typically lose that 1ºc through our head or face, which pokes out of the duvet.
“But if you’re sleeping in a room which is too warm, your body’s core temperature is unable to that heat and your sleep will be disturbed.”
People who are sleep deprived will have more intense sleep, the experts said, which leads to greater brain activity during sleep.
This increased brain activity makes you dream more, and makes your dreams more vivid - and more nightmarish.
He added: “Unfortunately, that goes for nightmares, which can be intense.”
Dr Stanley, who is also a member of the European Sleep Research Society, urged sleepers to avoid blasting out the heating during the night, and to keep a window open if possible.
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He also said sleepers should keep under natural fibres, cottons and silks when in bed, and should avoid eating late at night as this increases your internal body temperature and makes it harder for you to lose heat.
Disturbed sleep also means you are more likely to suffer ‘Rapid Eye Movement’ (REM) sleep, which makes you physically act out vivid, often unpleasant dreams with loud noises and sudden arm and leg jerks.
Dr Stanley added: “REM sleep occurs during either very light stage, or deep stage of sleep, both of which can be brought on by your sleep being disturbed by the ambient temperature.
“It’s during the REM phase of sleep when brain-waves behave similarly to being awake. This is the time nightmares typically occur.”
The UK Sleep Council issued similar advice this spring.
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They said: “Maintain an ambient (background) temperature in your room. If you’re too hot or too cold, you won’t sleep soundly.”
The US National Sleep Foundation added: “If your room is cool, rather than warm, it will be much easier to shut your eyes for the night.”
Home heating expert Steve Watson, an engineer with national installation firm STL Heating & Energy, says keeping a cool bedroom could also save you hundreds of pounds a year.
He reasoned: “Studies have shown that turning your thermostat down by just 1ºc can save you around £100 on your annual heating bill.
“And agreeing on a bedroom temperature can also help you to avoid the dreaded ‘thermo-spat’ - an argument about how hot the room is.”
