This summer we've already seen record-breaking hot weather and have been told to expect more in the future. We've asked our experts, Marc Holl, Head of Primary Care and Dr Unnati Desai, National GP Lead, to tell us the truth about some of the most well-known myths.
You shouldn’t swim for an hour after eating
Many people are told that swimming after eating can cause cramping or stitch, which makes it hard to swim and can lead to drowning. However, there's no evidence to say that this is true.
We do know that intense exercise deviates blood flow from the digestive system to muscles and skin – similar to our fight-or-flight response. This can lead to cramp, but usually only happens in athletes taking part in marathons or triathlons so it’s unlikely to happen during recreational swimming.
You don’t need to stretch before exercise because you’re already warm
Warming up before exercise has very little to do with your body temperature. It allows your heart rate to increase slowly so that when you start to do more high intensity workouts, your heart is ready to make that transition.
Warming up also moves blood flow to your muscles, preparing your body for the exercise. This will lessen the likelihood of injury and will also lead to a better workout session.
It can be dangerous to exercise in warm weather and if you do decide to exercise, it’s important to take precautions such as wear sun cream, exercise at cooler times of the day and stay hydrated. It’s also important that you warm up beforehand, even if you’re already warm.
Hot drinks cool you down when it’s hot
When your body’s internal temperature begins to rise, your hypothalamus (a small region in the brain) informs your sweat glands to cool you down by producing sweat.
The cooling down process occurs when the sweat is evaporated off your skin, and this process is called ‘heat of vaporisation’. The heat on your body is used as a form of energy to evaporate your sweat, which then cools you down. This is why it’s important to replenish your body’s water supply by staying hydrated.
Warm drinks cause your internal body temperature to rise which helps you sweat, leading to the heat of vaporisation process – resulting in cooling you down.
It’s possible to overhydrate
It’s always recommended to keep hydrated by drinking plenty of water during warms spells to replenish the water our bodies lose when we sweat, however it's often asked if you can overhydrate.
The answer is yes, the body can overhydrate but this usually happens if someone has a pre-existing disorder that affects the body’s ability to excrete excess water or increases the body’s ability to retain water.
It’s unlikely that you will overhydrate by drinking too much water as normal kidneys are very efficient in excreting the excess water. So, keep hydrating!
The sun can affect your mood
Many of us find that we feel happier on sunny days compared to gloomy winter ones. This isn’t just because you can go out and meet with your friends, it’s down to neurotransmitters in your brain, such as serotonin and melatonin, which are impacted by exposure to sunlight and vitamin D levels in your body.
Serotonin is a pre-cursor to melatonin and its synthesis is in part activated by Vitamin D. Serotonin and melatonin are neurotransmitters that help regulate the sleep-wake cycle - serotonin by promoting wakefulness and melatonin by promoting sleep. Serotonin also helps regulate mood by boosting positive feelings of happiness and calmness, promotes memory and focus, and promotes healthy gut digestion.
Studies also show that not enough exposure to sunlight can lead to a dip in serotonin which can lead to depression and Seasonal Affective Disorder (SAD). So, now you have a great excuse to go out and enjoy the sunshine!
Hot weather makes arthritis worse
Verdict: Depends on the individual
Many people who suffer from various forms of arthritis claim that temperature changes increase the pain caused by their arthritis. Some are more affected by hot weather, some by cooler weather.
No one knows exactly why this happens. It could be caused by a number of factors. One such factor could be that humidity and increased temperature can change how thick the fluid is in the joints which can make them feel stiff and inflamed causing pain.
There are a number of ways to combat the flare up of pain, through hydration, staying active and getting a measured amount of vitamin D through sunlight.
If you find that you’re really struggling with arthritis pain, Nuffield Health has a free-to-access Joint Pain Programme delivered with the expert guidance of a Rehabilitation Specialist, using a combination of education and physical activity, as well as psychosocial support. This will equip you with the knowledge and practical experiences to better manage your pain long term and achieve your goals.
Tanning isn’t bad for your skin
During hot weather, many people run outside to sit in the sun, all in the aim to get that perfect tan, however, not many of us know what it means for our skin when it tans.
Tanned skin, from a aesthetic viewpoint, is often perceived as a sign of health – but this is far from the truth. Tanned skin is a sign that your skin has been exposed to ultraviolet radiation and is the body’s way of protecting the genetic materials (DNA) in our skin cells from radiation. Damaging your skin cellular DNA can result in a loss of control of how and when a cell grows and divides, increasing the likelihood of skin cancers.
The idea that once you’re tanned you’re more protected is also a myth, as UV rays can still penetrate and cause damage.
However, sun exposure does have some health benefits such as increasing vitamin D levels, improving mental health and improving certain medical conditions, like psoriasis but only in moderate doses.
Hot weather can affect your period
Many people who experience periods don’t realise that hot weather does affect your periods. It can affect the length of your period, how heavy it is and can aggravate the symptoms such as fatigue, stress and acne.
This can be caused be dehydration and hormone fluctuation, which can cause your body to create more water and salt than usual. It can also be caused by a decrease in melatonin production, a hormone that tells your body when it’s time to sleep, which makes it harder to sleep. You also use more energy when you’re menstruating, which can contribute to the fatigue.
You can tackle these affects by exercising safely, reducing salty snacks and staying hydrated.
Hot weather makes you sleepy
Hot weather does make us sleepy because our body has to work harder to regulate internal temperatures. All this process uses up a lot of energy which can make us fatigued and sluggish.
To prevent feeling particularly tired, make sure you stay hydrated, as it makes it easier for the body to cool itself down.
It’s bad to sleep with the fan on
It can be hard to sleep in hot weather which is why many of us turn to a fan. Fans are a great way to stay cool, especially at night, but having one on you permanently overnight can cause issues. Having rapid air flow hitting you constantly over a number of hours can have a drying effect. It can dry out your mouth, nose and throat and can cause an over-production of mucus which can lead to headaches, a sore throat and a stuffy nose.
None of these issues are particularly serious, but they are good to be aware of.
Last updated Thursday 11 August 2022
First published on Tuesday 9 August 2022