We all know hormones have a lot to answer for – the wild mood swings, the monthly acne, the brain fog – but do you know just how many everyday processes your hormones have an influence over? As women, we tend to only think about hormones in terms of PMS, pregnancy and the menopause, but there's so much more to our clever endocrine system than just regulating our fertility. We spoke to hormone doctor Helen Simpson, from The Society for Endocrinology, about all the things you never knew your hormones were controlling.
1. Keeping you alive
First up, the basics: 'A hormone is a chemical substance that goes from an endocrine gland into the blood stream and acts on, often, a distinct part of the body,' Helen says. 'We have lots of different endocrine glands, the main one being the pituitary gland, which is about the size of a pea and sits just outside the bottom of the brain.'
The pituitary is a kind of control centre – it produces hormones that in turn affect the thyroid gland in our neck, the adrenal glands, which live above our kidneys, and our ovaries (or testes). 'The pituitary is a pretty fundamental gland that controls all those systems, and creates hormones that act on other glands, so that they then make different hormones,' Helen explains.
We'll get into all the other functions in a bit, but perhaps the most crucial hormones you've never heard of are glucocorticoids, which are produced by the adrenal glands. 'They're essential for life. If someone took away your adrenal glands, and you couldn't make that hormone, you'd basically become really sick and die. They regulate our sugar balance, our water balance, and our blood pressure,' Helen tells me.
2. Your weight
The thyroid, which we mentioned earlier, is also a really fundamental gland. It produces a hormone called thyroxine, which controls the metabolic rate of our cells, or how fast our bodies work. 'When the thyroid gland is overactive, people can get very thin, lose weight, get sweaty, shake, and their appetite can go up but they'll still be losing weight,' Helen says. Conversely, an underactive thyroid can cause weight gain – as well as tiredness, cold skin, a slowed heart rate, and memory problems.
Growth hormones produced by the pituitary gland can also have an impact on your weight. These hormones obviously play a huge role when we're growing up, but continue working on us as adults to help metabolise fats. 'These hormones affect our muscle and fat balance,' Helen says. 'Growth hormones work through the night to help your fat stores release energy for the body.'
Incidentally, hormones are also to blame if your boyfriend has less body fat and sees quicker gains at the gym than you – men's higher levels of testosterone help build muscle, which speeds up your metabolism.
3. The strength of your bones
Next to the thyroid, we also have four glands called the parathyroids, which control our calcium balance – and, as we all know from that Petit Filous advert, that's really important for bone density and keeping our bones strong. They're not the most interesting glands in the endocrine system but can cause big problems if they go wrong.
4. When you're thirsty, how much you have to pee and hangovers
Another really important hormone produced in the pituitary is called vasopressin, which controls the water levels in our body. 'Our body's really, really tight at controlling water. If the body feels that it's too dilute, vasopressin acts on the kidneys to make us pee more. If we get very dehydrated or very hot, the body releases less and we pee less – that's when our urine goes really dark,' Helen explains. Alcohol disrupts this hormone, hence the hangovers.
'Water's one of the most tightly controlled mechanisms in the body, which is regulated by hormones. Aldosterone, which is a hormone from the adrenal gland, also controls the salt balance in the body,' Helen adds.
5. How hungry you are
Hormones also tightly control our levels of blood glucose (or sugar, to you and me). 'Insulin comes from the pancreas and helps regulate our blood sugar level. In people with type one diabetes, the pancreas can't make any insulin, so it's a life-threatening condition if not treated with insulin injections,' Helen explains. 'In type two diabetes, when people are overweight, the body can't manage to control the blood sugar with the insulin that it makes, so it needs a bit of help.'
As well as controlling our blood sugar, there are also hormones that work as part of a complex communication system between the brain and the gut, telling us when we're hungry and when we're full up. 'Those hormones control hunger and satiety, so they help to control our appetite and our eating urges,' Helen says.
6. Your sex life
Ok, onto the really important stuff… Our sex hormones might be a right royal pain in the uterus at certain times of the month, but they also help keep us horny and wet. 'Testosterone and oestrogen are both needed for libido and attraction – although it's not purely hormones that control who you fancy,' Helen says.
Oestrogen also helps keep your vagina pink and moist, like a natural lube – which explains why fluctuations in hormone levels, whether caused by hormonal contraception, an early menopause, or your natural menstrual cycle, can have an impact on both your libido and your sexual function.
7. How you bond with everyone from your dog to your soul mate
Obviously, it goes without saying that love is more complicated than just a chemical reaction, but the hormone oxytocin is commonly credited with helping us bond with our loved ones. It's released during physical contact, so a cuddle with your pet, a drunken hug with that girl you just met in the loos, or a touch of sexy spooning can all help you to bond on some level.
However, Helen adds, there's still more research to be done on oxytocin and bonding behaviours in humans. What we do know from animal research is that we can get some serious #relationshipgoals from voles, those loved up little critters.
8. Your mood
We all know PMS mood swings are down to hormonal changes during our monthly cycle. Changes in oestrogen affect our levels of the feel-good neurotransmitters dopamine and serotonin, which is why women typically experience more cyclical mood changes than men.
The adrenal gland, as the name suggests, creates adrenaline hormones – the kind we associate with the life-preserving fight, flight or freeze response, which can make you feel anxious in stressful situations. Cortisol, commonly known as the 'stress hormone' is also produced by the adrenal glands. High levels of this hormone, caused by chronic stress, can cause serious long-term health problems.
Finally, sleep. Some of our hormones change in what's called a circadian rhythm, meaning levels fluctuate depending on the time of day. 'They're probably not the primary driver for making us go to sleep but, for example, cortisol goes up first thing in the morning, between 6 and 8, so it peaks in getting your body ready for the day,' Helen explains. 'These hormones get disrupted if you have jet lag or work irregular shift patterns.'
There's also melatonin, which peaks at nighttime and is known as the 'sleep hormone' for its ability to bring on sleepiness. Melatonin release is affected by daylight, which is why it's harder to sleep during the day, or if you have problems with your vision.
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This article originally appeared on The Debrief.