Serotonin: definition and meaning
Serotonin is a chemical messenger, or neurotransmitter, that helps regulate mood, sleep, appetite, digestion and pain. Most of the body's serotonin is made in the gut, but the small amount in the brain has a big effect on how we feel. Estrogen supports serotonin activity, which is one reason mood can shift across the menstrual cycle.
Serotonin and your cycle
Estrogen boosts serotonin production and receptor activity. When estrogen and progesterone fall in the late luteal phase, serotonin signaling appears to dip in people who are sensitive to the change. That's thought to explain several PMS symptoms at once:
- Low mood, irritability and tearfulness
- Carbohydrate and sugar cravings, as carbs help the brain make serotonin
- Poorer sleep
- Feeling more sensitive to pain
Why SSRIs work fast for PMDD
Selective serotonin reuptake inhibitors (SSRIs) raise serotonin activity. For depression they take weeks to help, but for PMDD they often work within days, which is why some people take them only in the luteal phase. That quick response is one of the strongest clues that serotonin is central to premenstrual mood symptoms.
Supporting serotonin naturally
There's no food or supplement proven to raise brain serotonin directly, but things that steady mood help: regular exercise, daylight, steady sleep, regular meals with complex carbs and protein, and limiting alcohol. Read why mood changes across the cycle and what causes PMS. Related: premenstrual syndrome.
Frequently asked questions
Does serotonin drop before your period?
Research suggests serotonin activity changes with falling estrogen, especially in people with PMS or PMDD, though it's hard to measure directly in the brain.
Can low serotonin cause cravings before a period?
It's a likely contributor. Carbohydrates help tryptophan reach the brain, where it becomes serotonin, so cravings may be the body seeking a mood lift.
Is a serotonin blood test useful for mood?
No. Blood levels mostly reflect gut serotonin and don't tell you about mood or PMS.
Sources
- Cleveland Clinic: Serotonin
- ACOG: Premenstrual Syndrome (PMS)
- Office on Women's Health: Premenstrual dysphoric disorder (PMDD)
This page is for information only and isn’t medical advice. If something worries you, please talk to a doctor.
Keep reading
Menstrual cycle mood: how you feel in each phase, and whyHow menstrual cycle mood changes through all four phases: what hormones do, why some people feel it more, and how to learn your own pattern.
SSRIs for PMDD: definition and meaningSSRIs are antidepressants that are a first-line treatment for PMDD. How they work, luteal-only vs daily dosing, side effects, and what to ask your doctor.What is premenstrual dysphoric disorder (PMDD)?PMDD (premenstrual dysphoric disorder) is a severe, cyclical mood condition in the week or two before a period. Symptoms, diagnosis and treatment options.
What causes PMS?What causes PMS? Not abnormal hormones, but some brains reacting more strongly to the normal rise and fall of estrogen and progesterone. What makes it worse.
PMDD treatment: options to discuss with your doctorPMDD treatment explained: SSRIs including luteal-phase dosing, the drospirenone pill, CBT, GnRH options and lifestyle steps, plus how to find the right care.