Why mood, appetite and sleep shift

The hormone shifts from the previous lesson reach the brain and appetite too.

Mood and PMS

Many people notice physical or mood changes in the days before their period. When these happen month after month and affect normal life, they are called premenstrual syndrome (PMS). Mood-related symptoms include irritability, anxiety, crying spells, depression, angry outbursts and trouble concentrating. A severe type, premenstrual dysphoric disorder (PMDD), affects a small percentage of women.

Myth: PMS is all in your head.

If anyone ever told you that, or you wondered it yourself, you're in very good company. It was a common belief for a long time. Researchers now find real biological differences in how the brain responds to the hormone changes of the cycle,¹ and PMDD is recognized as a medical disorder that can be treated.^2,3 You weren't imagining it.

Why it happens. Most of what researchers know comes from studies of PMDD:

• Symptoms rise and fall in step with the hormone changes of the cycle.
• A key factor appears to be an unusual response by the brain and nervous system to those changes in hormones.
• Brain imaging studies point to differences in how two chemical messengers, serotonin and GABA, pass signals between nerve cells. These studies are limited.¹
• Genes appear to play a part.
• Medicines called SSRIs, which act on serotonin, help some people with PMDD.

What can help. For mild to moderate symptoms, ACOG and the NHS suggest:

• regular exercise, such as brisk walking, running, cycling or swimming
• a regular sleep schedule
• relaxation, like breathing exercises, meditation or yoga
• changes in diet: more complex carbohydrates like whole grains, beans and lentils, calcium-rich foods, and less fat, salt, sugar, caffeine and alcohol

Keep a diary of your symptoms for at least 2 cycles and take it to your doctor if symptoms get in the way of your life.

Cravings and appetite

Hormones influence appetite. One review found that estrogen reduces food intake, while progesterone may increase appetite.⁴ After ovulation, progesterone is high.

A review of 15 studies with 330 women found that people ate about 168 more calories a day on average in the luteal phase than in the follicular phase.⁵

That is an average. The studies used different methods, and they measured how much people ate, not which foods they craved.⁵

Sleep

Many people say they sleep worst around their period. In sleep studies of healthy women, ratings of sleep quality were lowest around menstruation. But the timing and makeup of sleep stayed fairly steady across the cycle. The measured changes were small: in the luteal phase, slightly less REM sleep and a small change in a type of brain activity during sleep.⁶

Body temperature is also higher after ovulation, as covered in the last lesson. Whether that explains poorer sleep isn't established.