Summer heat waves are trickiest at night. When it’s too hot to sleep, you toss and turn on a sweat-soaked mattress. When you resort to air conditioning, you can wake up with dry skin in an ice-cold room.

Keeping a trusty fan blowing on you throughout the night seems like it would be the best middle ground for staying cool on humid evenings — but they can also bring on some annoying side effects.

Doctors have now revealed the ways that the constant breeze of a fan can affect your health and shared their top tips for reducing any potentially undesirable impacts.

1. Allergies or asthma

Turning a fan on throughout the night can stir up allergens in the room like dust, pollen and pet dander, which can trigger allergies, hay fever or worsen asthma symptoms.

“If your airway is already reactive and sensitive, the combination of circulating allergens and dryness can make symptoms like coughing, wheezing, or congestion worse,” says Dr. William Lu, the medical director at digital sleep clinic Dreem Health, according to Tom’s Guide.

The fan blades themselves also often have dust collected onto them, which only adds to the particles circulating around the room.

2. Stiff muscles

When cool air is concentrated on one part of your body for a prolonged period of time, it can cause muscles to tense up or cramp due to super localized blood flow.

Because of this, in addition to the fact that your body often stays still for hours at a time during sleep, you can wake up feeling sore, according to a Healthline article reviewed by certified physician Raj Dasgupta. It’s especially common to have a stiff neck.

3. Congestion

Constant airflow can dry out your nose, mouth and throat, prompting your body to produce more mucus in an attempt to combat the dryness. Overproduction of mucus can cause congestion, bringing on symptoms like a sore throat, stuffy nose, coughing and a sinus headache.

Dr. Julius Goh, an ENT specialist, wrote on The ENT Doctor blog: “The mucociliary clearance system (the microscopic hair-like cilia that sweep mucus and allergens out of your nasal passages) needs moisture to function. Dry it out and you’re essentially paralyzing your own nasal immune defense. Allergens sit longer. Symptoms worsen. You wake up sneezing before you’ve even had breakfast.”

4. Dry skin

A steady stream of cool air can also dry out your skin and eyes, making it even worse if you already deal with eczema, psoriasis or dry eye, according to a Verywell Health article reviewed by certified pediatrician Jonathan B. Jassey.

Reducing negative side effects

If you are still determined to stay cool this summer by sleeping with a fan on, there are precautions you can take to lower the chances of waking up with a sore neck or dry skin.

1. Aim the fan away from you or have it oscillate

Keeping your fan at a distance and pointed away from you will help manage the temperature in your room and keep air flowing without blowing air directly at you.

Better yet, if your fan has an oscillating feature, be sure to turn it on to ensure that the airflow is evenly distributed instead of drying you out.

“If you find that you get better rest when sleeping in a cooler temperature, then you should not avoid using a fan entirely,” Dr. Michael DeShields, the clinical advisor of the New Jersey-based Discovery Institute facility, explained. “You can easily eliminate possible negative consequences of using a fan during your sleep period by cleaning your fan at least periodically, replacing the HVAC filters, maintaining your home’s humidity level (between 30-50 percent), and positioning the fan so that it blows directly away from your head throughout the entire night.”

He advised, “In addition, if you awaken with dry nasal passages, you might consider spraying a saline solution into each nostril prior to going to bed.”

2. Keep your home clean

Vacuuming and dusting can help prevent dust and other allergens from being spread around your room. It’s also worth making sure to keep the blades on your fan clean to prevent particles from flying around even more.

Although it can cause pesky side effects, sleeping with a fan on is not likely to cause any longterm damage or serious illness. However, it is worth noting that fans do not cool the air — they move air across the skin, which helps sweat evaporate and make people feel cooler.

I recently wrote a feature on bone strength and how to increase it, hoping to help people swerve injury and stay mobile for longer. The key, experts say, is to challenge the body with exercises like running, jumping and lifting, which place load on the bones and prompt them to adapt.

Underneath, someone wrote: “I just tried lifting some weights, sprinting and jumping, as you advised. I’m in A&E now and a consultant will be down to see me shortly.”

A joke, undoubtedly. Yet this is a concerningly common belief: exercise will hurt me, I dare not do it.

It also demonstrates a misunderstanding of the two fundamental principles behind any successful exercise routine. Once you learn these principles, they will keep you in enviable shape for the rest of your life. Below, I’m going to share them with you.

The first secret to successful exercise: identify your capabilities and get started

We should only tackle exercises that sit within our capabilities. That is how we avoid overstretching ourselves and suffering an injury.

Everyone has different capabilities. Elite athletes might be able to run 100 miles or chuck 200kg over their head, while a less fit person who leads a busy life might struggle to run a mile or lift a light dumbbell.

However, while everyone has different capabilities, the most important thing to note is that everyone is capable of something.

If you can’t sprint, you run. If you can’t run, you walk. If you can’t walk, you might try low-impact alternatives like swimming, or exercise machines which use other muscles to raise your heart rate.

A similar approach applies to strength training. If you can’t lift a loaded barbell, you might start with light dumbbells or a resistance band.

Often, people assume doing these more accessible variations of an exercise will have little impact. But science suggests this couldn’t be further from the truth.

A new meta-analysis found that people experienced a disproportionate amount of muscle growth in their first few months of strength training. As time went on, results continued, but at a reduced rate. This phenomenon often extends to many other health markers too, filed under the phrase “newbie gains”.

The key take home message here is that simply starting to exercise, in whatever form works for you, holds immense value.

As Dr Stuart Phillips of the American College of Sports Medicine puts it: “Training all major muscle groups at least twice a week matters far more than chasing the idea of a ‘perfect’ or complex training plan. Whether it’s barbells, bands or body weight exercises, consistency and effort drive results.”

The second secret to successful exercise: apply progressive overload

The other thing this meta-analysis highlights is, once you are into the swing of things with your exercise routine, you need to apply some form of progression to see continued improvements. This is called progressive overload, and it is the second key principle behind any successful exercise plan.

General movement in any form will be beneficial for your health. But for certain fitness perks such as increasing cardiorespiratory fitness, there comes a point where you have to challenge yourself every once in a while.

But again, this doesn’t mean suddenly running a marathon, sprinting 100m in sub-10 seconds or hoiking 100-plus kilograms from the floor. It just means gradually upping the difficulty of your workouts in line with your increasing fitness levels.

If I walked 10 minutes each day last week and it felt easy, I might walk 11 minutes each day this week, or consciously up my pace ever so slightly.

If I felt comfortable doing three sets of 10 goblet squats with a 12kg kettlebell last week, resting 60 seconds between each set, I might do three sets of 12 repetitions this week.

If I ran 5km in 30 minutes last week, this week I might try to run 1km in 5min 50sec (a slightly faster pace), rest for a few minutes, then repeat this four more times. This way, I have practiced running the same distance in less time.

In each scenario, I tweaked variables in my workouts to make them slightly more challenging – either by increasing the amount of work I’m doing or raising the intensity of the task.

The key is to stay within your capabilities, but try to experience the upper end. Doing this will widen your capability window – or, in simpler terms, make you fitter.

The reason this works is called the SAID principle, which stands for specific adaptations to imposed demands. This means the body will, handily, adapt to be better at the things you consistently do.

Regular aerobic exercise like running will likely result in a more efficient heart and lungs. Regular strength training will likely result in stronger muscles, bones, ligaments and tendons, among other perks.

But to trigger these adaptations, you have to put a persuasive business case forward to your body. That is the message an appropriately challenging workout sends.

The human body is an adaptation machine. It is capable of adapting to most challenges if given the right consistent messages, fuel, recovery and time – the possibilities are almost endless.

Who knows? Maybe some day, our dear reader might even be able to sprint, lift and jump without a trip to A&E.

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