Why Do Cycles Vary? Your Own Unique Rhythm

If your period doesn't show up exactly every 28 days, please don't worry, that's completely normal. Every body has its own rhythm, and yours is still figuring out its beat. Here's why cycles vary, and what counts as normal.

The "28-day cycle" myth

You may have heard that a cycle should be exactly 28 days. That number is really just an average. Healthy cycles can be:

• Shorter: around 21 days
• Average: around 28 days
• Longer: around 35 days
• Variable: a little different each month

All of these are completely normal.

What sets your cycle length

• Genetics. Age at first period, and how regular cycles tend to be, do run in families, so it's worth asking your mum or an older sister what theirs were like. Cycle length itself is a much weaker match: when researchers go looking for a genetic effect on how many days your cycle lasts, they find only a small one, so don't expect yours to line up with hers.
• Hormones. Your cycle is run by hormones, and their balance decides when you ovulate and when your period arrives.
• Age. The first few years are often irregular, the middle teen years onward are usually the most regular, and much later in life cycles become irregular again.

Things that can shift your cycle

• Stress. This is one of the biggest disrupters. When you're stressed, your period might come late, run lighter or heavier, or skip a month.
• Sleep. Your body needs good rest to balance its hormones. If you are 9 to 12, aim for 9 to 12 hours a night, and if you are 13 or older, aim for 8 to 10, keep a steady sleep schedule, and ease off screens before bed.
• Exercise. Training very hard, especially when you're not eating enough for how much you're moving, can make periods lighter or stop them completely. That's your body flagging something, and it's a reason to tell an adult and see a doctor, not something to fix by changing your training on your own.
• Big diet or weight changes. Your body needs enough fuel to run a cycle, so periods can get lighter or stop when someone isn't eating enough for everything their body is doing. If that sounds like you, it's one to take to an adult you trust and a doctor together. It is not something to sort out by changing what you eat on your own.
• Being sick. An illness, especially with a fever, can delay your period while your body focuses on getting better.
• Travel. Crossing time zones can confuse your body's internal clock and nudge your cycle.

Why cycles are irregular at first

When you first start getting periods, it's totally normal for them to be all over the place. Your body is still learning, and the hormone system behind your cycle takes time to mature, a bit like your body practising. Here's a rough idea of what to expect:

• First year: cycles might swing anywhere from 21 to 45 days
• Second year: starting to settle into a pattern
• By year three: most people have a fairly predictable rhythm

Finding your own pattern

Even while things are irregular, a little tracking helps you spot patterns, stay prepared with supplies, and learn what's normal for *you*. For 3 to 6 months, jot down:

• When your period starts
• How long it lasts
• How heavy it is
• Any symptoms you notice

Over time you'll start to see your average cycle length, the signs that your period is on its way, and the days you tend to feel your best. Once you know your pattern, you can predict your period, plan around big events, and notice quickly if something seems off.

When to talk to a doctor

Most variation is perfectly normal, but it's worth checking in with a doctor if:

• You haven't had a period by age 15, or it's been more than 3 years since your breasts started developing
• Your periods stop for more than 3 months after having been regular
• Your cycles are consistently shorter than 21 days or longer than 45
• Your periods are extremely heavy or painful
• Anything is worrying you

Remember

There's no such thing as a "perfect" cycle. What matters is getting to know YOUR body and what's normal for you. Your rhythm is one of a kind, just like you, and Sosô is here to help you find it. 💛