Do wet hair make you ill? Does a cold shower ward off a cold? As winter bites, this fact check will help you separate persistent myths from science.
Not everything we say about our health in cold weather is true. Time to sort the myths from the science.
Belief: Wet hair in the cold makes you ill
False. Colds are always caused by viruses, not by cold alone or wet hair in chilly weather. Without contact with a pathogen, there is no infection.
Studies do show that strong cooling of the body surface, for example through wet clothing or cold air, can reduce blood flow in the mucous membranes. This can weaken local defences and allow existing viruses to multiply more easily. Keeping warm can sometimes help, but a cold always requires a pathogen.
Belief: Cold showers prevent illness
Unclear. A Dutch study with around 3,000 participants found that people who took daily cold showers of 30 to 90 seconds felt fitter and reported fewer sick days, but were not objectively signed off sick less often.
Cold showers can stimulate circulation and briefly increase blood flow, but proven protection against colds is lacking. Experts advise starting slowly if you want to try it, for example with contrast showers that cool the body step by step.
Belief: Women feel the cold more quickly than men
True. Women perceive cold more intensely for biological reasons. Men have more muscle mass and burn more energy, generating heat, while women typically have a higher proportion of body fat.
Hormonal fluctuations also influence temperature perception. Studies indicate women find around 24 degrees Celsius comfortable, while men feel at ease at about 22 degrees. The difference is measurable, not imagined.
Belief: Alcohol warms the body from within
False. A glass of whiskey or a mug of mulled wine may create a fleeting sensation of warmth, but it actually cools the body. Alcohol dilates the skin's blood vessels so warm blood flows to the surface, producing a cosy feeling.
This is deceptive because heat is lost to the environment more quickly, which lowers core body temperature. Alcohol can disrupt the body's natural thermoregulation.
Doctors recommend avoiding alcohol in the cold and warming up by being active or drinking hot non-alcoholic drinks.
Belief: Blood pressure is higher in cold weather
True. Blood pressure varies over the day, rising sharply after waking and increasing through the morning. Sex, age, lifestyle and environment all play a role.
Temperature differences matter too: In winter blood pressure is higher than in summer, because the blood vessels constrict in the cold, which causes a rise in blood pressure, health experts say.
Persistently high blood pressure can seriously damage the brain, heart and kidneys over time, the Heart Centre at Berlin's Charité said. High blood pressure is defined as values consistently above 140 over 90.