IT’S a strange phenomenon that some of us are always freezing, while others are absolutely boiling hot.
You can be shivering in five layers at exactly the same time as your partner is flinging open windows, fanning themselves.
It’s not just to do with your weight and size, but also your age, gender, diet, sleep patterns, lifestyle and even your happiness.
Humans are warm-blooded, with our body temperature averaging around 37C.
Warm-blooded simply means we can regulate our internal body temperature, independent of environment, while cold-blooded animals are subject to the temperature of their surroundings.
But while all humans are "homothermic”, our body temperatures can vary wildly, as a fascinating D News video explains.
Temperature regulation starts in the brain and is controlled by hormones, which take into account the body’s core temperature and the temperature of the outer skin.
The hormone oestrogen is part of the regulation process, according to the Lancet.
Women are usually colder than men, and older people colder than younger. People who are more active tend to have warmer hands and feet overall than those who don’t.
Men tend to have more muscle mass and women more fat. The working of muscle generates heat, while fat cells store it. Researchers at the University of Utah found that men’s hands were 32.3C on average, while women’s were 30.7C.
Women’s bodies have to work harder to keep their core body temperature up, leaving fewer energy resources to warm the extremities.
The time of the month can come into play too. The menstrual cycle can alter a woman’s body temperature by several degrees.
Fatter people tend to feel warmer because their core organs are warm, although their extremities are actually colder.
People with lower BMIs tend to feel colder because blood pumped through the extremities needs to be warmed up significantly when it gets back.
We regulate our internal temperature through thermo-regulator cells in our skin, which detect cold and constrict our capillaries and blood vessels in a process called "vasoconstriction”, slowing the speed of our blood flow.
People who smoke have more vasoconstriction, cooling the extremities, while active people have warmer hands and feet.
And it’s not just about being physically hot, it’s also our perception of temperature.
If you’re surrounded by people you’re comfortable with you will feel warmer. A Canadian study found that people who are lonely or feel isolated are more aware of a cold body temperature while socially connected people tend to feel warmer.