When the temperature rises beyond what's comfortable, the first thing many of us do is dial down the temperature in the shower, step into the kids' paddling pool, or start drinking icy cold drinks.
This might feel good in the moment, but when trying to sleep in the heat, "getting into ice cold water" is actually completely counterproductive, warns Dr Bostock, aka The Sleep Scientist.
"Getting into ice-cold water gives your nervous system a bit of a shock, and your immediate reaction in cold water is for your blood vessels to constrict because it's trying to protect you," she says.
"What you actually want is lots of blood flow going to your extremities, so research suggests that a lukewarm bath or shower actually helps with the blood flow to your skin, and that means when you get out of the shower, you're going to lose heat more easily."
To clarify, host Ben Shephard says: "So the more blood flow you have to the skin, the better your body is at controlling heat loss, so you will cool down quicker?"
"Absolutely," says the doctor.
"There is absolutely no doubt that heat makes things harder. We've all got an internal rhythm and body temperature that naturally peaks at about 5 or 6 pm, and we get coolest at about 2 or 3 am in the morning, so there's this natural dip at bedtime," she says.
"That cooling of our internal body temperature is like a cue for sleep, so if our ambient temperature around us is too hot, there isn't enough temperature gradient.
"We find it harder to lose heat, so it's harder to fall asleep, and when we finally get to sleep, we get less deep sleep which is really restorative. We also get less REM sleep, which is really good for our emotional balance, so we wake up feeling a bit tired and a bit irritable," she says.
To help us out this week, the doctor shared her other tips on sleeping in the heat:
- Find the right sleeping temperature: The "ideal" temperature for sleeping is "just a little bit cooler than room temperature," the doctor says. "It doesn't need to be much. Anything between 15 and 20 degrees."
- Create airflow through the house - particularly on the ground floor: "Heat rises, so if you do have a bedroom on the ground floor, that may be worth moving into," she says.
- Avoid the 'greenhouse effect': As soon as the sun rises, you have the conditions to create a very warm environment in your home, so the doctor recommends closing the blinds during the day.
- Stay well hydrated: The symptoms of dehydration can be easy to miss, as fellow ITV guest Dr Amir Khan revealed exclusively to woman&home. Dr Bostock says it's important to stay "well hydrated" to avoid these. "We lose heat through sweating, mainly so we need to be well hydrated," she says. "Drink frequently throughout the day."
- Avoid ice baths: The true "worst" thing to do in a heatwave is to get into an ice bath, the doctor also says. While some people like to have an ice bath every day, we've already covered some research that suggests these aren't all they're cracked up to be anyway.
- Be aware of other factors affecting your sleep: The doctor reminds us that those going through perimenopause and experiencing night sweats may find it harder to regulate their temperature, along with older people. Those with sleep apnea may find their symptoms get worse in hot weather, she says.
