DR MICHAEL MOSLEY: Why being cold is good for your brain, sleep and waistline… And it helped my son after his first-floor plunge

As we have all noticed, it has been very cold lately. My family lives in an old house, which is difficult to keep warm, and our boiler has broken down again.

But as we huddle around the electric heaters, I console myself with the thought that while the cold can be dangerous, especially if you're older and more vulnerable, it also brings some surprising health benefits.

For example, did you know that it is easier to exercise in the cold? Or that you sleep longer and better if your bedroom is fresh? Or that lowering the room temperature by a few degrees could reduce the risk of developing type 2 diabetes?

I learned all this and more while creating my new podcast series Cold Therapy (out next week), which looks at how cold can be harnessed to improve your health in ways you might not expect.

One of the reasons for my particular interest in the power of the cold is that it helped protect my eldest son, Alex, many years ago.

When he was eleven, he fell from a first-floor window while sleepwalking and fractured his skull. He was found barely conscious by a neighbor who happened to pass by our house around midnight.

While we waited for the ambulance to arrive, we pressed bags of frozen vegetables wrapped in tea towels onto his skull, which is standard procedure. This reduced pain and external swelling – it may also have helped reduce the risk of brain injury.

That's because cooling the head can slow and even prevent some of the processes that cause long-term brain damage after an injury.

In 2014, researchers from the University of Oxford published in the New England Journal of Medicine the results of a fascinating study that involved cooling babies who were at risk of long-term brain damage due to birth-related complications.

The babies were randomly assigned to be cooled to 33 degrees Celsius for 72 hours, or not; They were followed for years, and it turned out that those who were cooled down were much more likely to grow up with a normal IQ than those who received the usual treatment.

I'm happy to say that Alex has made a full recovery. Since then, I have used the cold bag or veg technique many times to treat minor injuries.

It works because the cold is an analgesic – temporarily slowing the speed of signals traveling through the nerves – and also because it causes vasoconstriction: the blood vessels supplying blood to the damaged area become narrower, reducing swelling and inflammation. (However, it is best to hold something cold against an injury for more than 20 minutes at a time, as this can cause tissue damage.)

MAKES PRACTICE EASIER

At this time of year, one of the last things I want to do is put on a tracksuit and go for a run.

But what I hadn't appreciated until now is that it's actually easier to exercise in the cold than when it's warmer. As Dr Chris Tyler, a physiologist at Roehampton University, told me: 'The optimal performance temperature for running is lower than you might think; for most recreational runners it is actually in the 10c to 11c range.”

In other words, if you're a weekend warrior or only an occasional runner like me, then running on a cool, but not freezing, day is easier and will likely make you fitter than running in the summer months.

And as for elite marathoners. . . Well, they perform best when it's even colder, somewhere between 4 and 8 degrees.

It's all about getting rid of excess heat. When we train in a warm environment, our muscles generate a lot of heat, which our body has to dissipate by, for example, sending a lot of blood to your skin and making you sweat.

When you run in the cold, you don't have to send as much blood to your skin, so your heart doesn't have to work as hard and you can move more without feeling exhausted.

IT INCREASES METABOLISM

We are often warned about the dangers of cold weather, and the charity Age UK says that the main living areas of older people should be kept at 21 degrees Celsius or above. But as long as you're healthy and active, you should be able to adapt to lower levels – and that can be good for your health.

For example, in 2018, researchers at Maastricht University Medical Center discovered that after ten days of living in a cold room (around 14 degrees Celsius) for six hours a day, people with type 2 diabetes experienced a significant improvement in their insulin sensitivity (the amount that your body needs to produce after a meal to bring your blood sugar levels back to normal) – overall it improved by 40 percent, which is as good as with medication.

The explanation for this is that as your body acclimates to the cold, you begin to produce more GLUT4, a protein that helps remove glucose from your bloodstream and delivers it into your muscles. Your fat metabolism also changes; the same study showed that staying in a cool room increased the amount of brown fat, which, unlike normal 'white' fat, burns a lot of calories.

YOU ALSO SLEEP BETTER

You may want to turn the thermostat down a bit, as there is some evidence that being cool helps induce longer, deeper sleep.

A 2016 study at the University of Sydney found that at a room temperature of 17 degrees Celsius compared to 22 degrees Celsius, people spent more of the night in the deepest phase of sleep (important for memory and overall brain health) and in rapid eye movements (REM). ) sleep – when you do most of your dreaming and which in turn is vital for consolidating memories and helping process emotions.

So keep your bedroom cool; Although I think it also helps to have someone nice and warm to cuddle with.

• Cold Therapy, BBC Radio 4, 9.45am weekdays, starts on Monday 11 December. All episodes available on BBC Sounds.

Better remedies for a stuffy nose

It's the season of stuffy noses and I've succumbed.

While the obvious solution may be a decongestant, I haven't done this myself. This follows a report from the US Food and Drug Administration, which concluded that products containing phenylephrine – a common ingredient – ​​when taken orally are virtually useless in clearing the nose. If you are going to take it, use a nasal spray.

Instead, I've tried steam inhalation, menthol, and using pillows to support myself in bed. Steam thins your nasal mucus.

I found that a combination of doing this and drinking plenty of water (which keeps you from becoming dehydrated and also thins the mucus) helps.

While there's no real evidence that menthol works as a decongestant, I found the scent oddly comforting (memories of Vicks rubbed into my chest as a child). I also came across evidence that because the fumes are so strong, inhaling them can fool your brain into thinking you're breathing through an unclogged nose.

I'm getting better, but at my worst I was propping myself up with pillows at night because gravity was causing snot to flow down my throat, reducing pressure on my sinuses.

Can we enhance the placebo effect?

The placebo effect is fascinating; the fact that a pill with no active ingredients can help relieve pain and other medical problems is impressive – and scientists are working hard on ways to harness its power.

But to make placebos more effective, they may need to be supplemented with something that causes real side effects.

That was the conclusion of a recent experiment from the University Medical Center Hamburg-Eppendorf in Germany. Volunteers underwent brain scans while pressing a hot object against their arms – they had previously used a nasal spray that they were told contained a powerful painkiller or a placebo.

In fact, all the nasal sprays contained water, but some were laced with capsaicin, a chemical derived from chili peppers that causes a mild burning sensation. The volunteers reported the most relief with the peppery water (which they thought contained a painkiller); Their scans also showed that the peppery water led to the greatest activation of nerve pathways that suppress pain. Despite decades of research, we still have more to learn about how to make the most of the placebo effect.