Hormones: the basics

What are hormones?

Hormones are chemical messengers that are released from endocrine glands to a target organ. They work throughout your entire body to make sure all of your organs and body systems are communicating well in order to work properly. They are released in response to a signal from your brain directly into your blood. Hormone secretion fluctuates over time and is dependent on many internal and external factors. Some common hormones include insulin, estrogen, testosterone, cortisol, melatonin, and vitamin D (yes, this is a hormone!).

Your hormone balance is regulated by the communication between your brain and your ovaries. Many factors interfere with your hormone balance, such as stress, diet, sleep, environment, and the natural aging process. 

3 Hormones You Should Know About


Estrogen is produced mainly in your ovaries and is responsible for the tissue development and maintenance of your reproductive system. It also increases the amount of neurotransmitters in your brain that play a role in mood, memory, libido, and sleep. It improves bone density, increases good cholesterol (HDL), and keeps your skin moist and elastic. 


Progesterone, also produced mainly in your ovaries, balances the effects of estrogen and is responsible for the function and growth of your reproductive system. It is very important for fertility -- it increases after ovulation to prepare and thicken your uterine wall for implantation (pregnancy). Also, it has a relaxing, calming effect in your brain, resulting in better sleep and reduced levels of stress. Like estrogen, it is important for bone health and cardiovascular health. 


Testosterone is a hormone that most people associate with men. However, it is important for women as well. It is produced in your ovaries and adrenal glands and is responsible for libido and sex drive. It is needed for muscle growth, bone strength and growth, cognitive function, and supports cardiovascular health. 

Hormones and your cycle

To understand hormones, it's important to know about the roles they play in during your menstrual cycle, which is the number of days between your first and last period and typically lasts about 28 days. 

Progesterone and estrogen are low at the start of your menstrual cycle (first day of bleeding). This tells your pituitary gland to produce follicle stimulating hormone (FSH) , which stimulates the growth and maturation of a follicle in your ovary containing an egg. This will increase estrogen to prepare your uterus for implantation. Estrogen spikes right before ovulation which triggers an increase in your luteinizing hormone (LH) -- marking the beginning of ovulation (egg is released from the follicle) around day 12-14. After ovulation, progesterone increases to prepare and thicken your uterine wall for implantation. If fertilization doesn't occur, progesterone and estrogen decrease and you start to shed your lining resulting in your period (day 1). And the cycle repeats itself again.