If you feel different at different points in your cycle, you're not imagining it: nearly everyone gets some symptoms before a period. Four hormones run the cycle, and they follow the same script every month.
Which hormone does what?
At the start of the cycle, your brain releases FSH (follicle-stimulating hormone), and a follicle, a small sac holding an egg, grows in the ovary. The follicle makes oestrogen, which builds up the lining of the uterus. When oestrogen gets high enough, the brain sends out a surge of LH (luteinising hormone), and a day to a day and a half later the egg is released. That's ovulation.
After ovulation, progesterone takes the lead and gets the lining ready for a possible pregnancy. If there's no pregnancy, oestrogen and progesterone both drop, the lining sheds, and your period starts.
Why do I cry at reels before my period?
Crying at a reel a couple of days before your period is something lots of people know, and it's one way PMS can show up. Nobody knows the exact cause yet, but it looks like some people are simply more sensitive to hormone changes than others.
It usually eases once your period starts, and the symptoms often go away completely by the end of it. You can make it easier, too: movement, proper meals and sleep help, and PMS that gets in the way of your life can be treated.
Why did the app get my date wrong?
The two halves of the cycle behave differently. Your period usually comes 10–16 days after ovulation, and for any one person that gap stays fairly steady. The first half is more flexible: in a stressful month ovulation can come later, and your period moves with it.
The app works from your past dates and can't know that ovulation was late this time. So think of the forecast like a weather forecast: "expected around this date". The more real dates you log, the closer it gets to your body.
What can you do this cycle?
Log how you feel for at least two cycles in a row, so you can see whether the hard days land before your period. Once you know your pattern, you can plan around it: a spare pad in your bag, and nothing on those evenings that could easily wait. And log the real first day of each period, because the forecast learns from your dates.
Common questions
What if my cycle isn't 28 days?
That's normal: regular cycles anywhere from 21 to 35 days are common. In a study of over 600,000 cycles, only about 1 in 8 lasted exactly 28 days.
If my periods are regular, am I ovulating?
Most likely, yes, and doctors tell people with regular periods exactly that. If it needs checking, say when a pregnancy isn't happening, a doctor can order a progesterone blood test about a week before your period.
Can hormones tell me my ovulation day?
Roughly. An LH test picks up the surge a day to a day and a half before ovulation, and slippery discharge tells you it's getting close. Morning temperature only rises afterwards. None of these is reliable protection from pregnancy, because sperm usually live for up to 5 days, sometimes 7, and the window is easy to miss.
In short
- Log how you feel for two cycles to see your pattern
- Log the real first day of your period so the forecast can learn
- Tough PMS can be treated, so show your notes to a doctor
Source: NHS: Periods and fertility in the menstrual cycle
Educational content; it does not replace professional medical advice.