Almost everyone notices something change before a period: mood, appetite, breasts, belly. For 2–4 in 100 it can seriously get in the way of life, and for everyone else it's milder and manageable. These days fall in the luteal phase, which usually lasts 10–16 days from ovulation to your period.
What happens after ovulation?
The empty follicle that released the egg turns into the corpus luteum. It makes progesterone, a hormone that gets the womb lining ready for a possible pregnancy. Your body temperature goes up by about 0.3–0.5 °C and stays there until your period.
If you're not pregnant, the corpus luteum fades, hormone levels drop and your period starts. This half of the cycle varies less than the first, so a late period most often means ovulation came late. If you've had sex, most pregnancy tests work from the first day your period is late.
Why do I feel like a different person before my period?
Lots of people get this, just to different degrees. The most common signs are mood swings, irritability, tearfulness, anxiety, tiredness and poor sleep. Physical ones include bloating, sore breasts, headaches, spots and food cravings.
It usually starts 1–2 weeks before your period, more often closer to it, and eases in the first days of bleeding. If it comes back cycle after cycle, you're not imagining it: doctors know PMS well, and it can be treated.
What helps you get through these days?
Regular movement all month, not just on the bad days, helps many people: for example, a brisk 30-minute walk on most days. Go to bed and get up at about the same time, weekends included.
It helps to cut back on caffeine and alcohol on these days. When anxiety hits, try slow breathing: in for a count of 4, out for 6. For a headache or sore breasts, ibuprofen or paracetamol can help, taken as the pack says.
When is it more than PMS?
Sometimes the days before a period hit so hard that it's difficult to work, see people or keep relationships going. This may be PMDD, a severe form of PMS, and it can be treated with antidepressants, talking therapy or hormonal pills.
If your mood is low all month and just gets worse before your period, it's worth checking for depression or anxiety. About half of people who seek treatment for PMS turn out to have one of them.
Common questions
Why do I crave sweet things before my period?
Food cravings are one of the most common signs of PMS, so you're definitely not alone. Eating a little every 2–3 hours and choosing slow carbs like wholegrain bread, grains and beans can help. A bit of chocolate is no crime, either.
Why don't my jeans fit the week before my period?
Before a period your body often holds on to water, which means bloating and a higher number on the scales. Try eating less salt on these days, and it usually goes away by itself once your period starts.
I don't get PMS. Is something wrong with me?
No, you're fine: not everyone gets PMS. You might not even notice mild changes, and doctors only call it PMS when symptoms get in the way of life month after month.
In short
- Log your mood every day to see your pattern
- Move for 30 minutes on most days, all month
- Eat a little every 2–3 hours
Source: NHS: PMS (premenstrual syndrome)
Educational content; it does not replace professional medical advice.