What are hormones?
Hormones are chemical messengers. Glands in your body make them and release them into your blood, which carries them to the places they work.
This network of glands is called the endocrine system. It controls growth, energy, sleep, mood and puberty.
The control centre
Puberty starts in the brain. A part called the hypothalamus sends a signal to the pituitary gland, a pea-sized gland just below the brain.
The pituitary then sends messages to the ovaries or testicles, telling them to start making sex hormones. This is like a chain of messages passed along.
Meet the messengers
Oestrogen: mostly made in the ovaries. It helps breasts develop, widens hips and builds the lining of the uterus.
Progesterone: also from the ovaries. It works with oestrogen to manage the menstrual cycle.
Testosterone: mostly made in the testicles. It deepens the voice, grows facial and body hair, builds muscle and starts sperm production.
Everyone makes some of each of these, just in different amounts.
Growth and energy hormones
Growth hormone: from the pituitary. It helps bones and muscles grow, and much of it is released during deep sleep.
Thyroid hormone: from the thyroid gland in the front of the neck. It helps set how fast your body uses energy and supports growth and brain development.
Hormones also affect your skin, sweat and moods, which is why puberty can feel like a lot at once.
When to ask a doctor
Hormone levels go up and down naturally during puberty. Feeling moody or tired sometimes does not mean something is wrong.
If you or your family are worried about your growth, energy or puberty timing, a doctor can check. Only a doctor should decide whether any tests or treatment are needed.