All the totally normal reasons why your period is so light

·6-min read
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Why is my period so light? 7 super normal reasonssteklo - Getty Images

Periods can be pernickety beasts, even if you've been having one for years, it can still sometimes sneak up on you, or switch up in intensity taking you by surprise. Bodies, eh? Periods can change from heavy to light from month to month, too – and if you're currently wondering why your period is much lighter this month, then you're not the first (or the last). Sometimes your flow can be heavy one month and ease all the way off the next, and the change can be worrying. But don't stress!

While some people get consistently light bleeds and others have to put up with heavy periods month after month, the rest of us are treated to a right royal mix up, and some skip bleeds altogether (but more on that, later). But – as annoying as the unpredictability is – it's likely nothing to worry about.

Still, being the ever-curious creatures we are, we wanted to know why, exactly, some people get light periods and when it's time to book in for a chat with the GP.

What is the definition of a 'light' period?

According to INTIMINA gynaecologist, Dr Shree Datta, there's no hard and fast rule of what comprises a 'light period' as everyone's bodies are different, but generally it can be defined as losing less than 30 to 35ml blood during your period. "Unless you're using a menstrual cup, that can be hard to measure," she adds. "So it's also worth considering how heavy your normal periods are to gauge whether your flow is light for you. It's important to remember that your cycle can vary from month to month."

Dr Datta adds, "If your last period was heavy, for example, your next one may be naturally light."

Still want to know why your period might be so light this month? Sit tight – Dr Datta, along with GP, Dr Tatiana Lapa, are here to explain why... and it turns out there are various factors that can contribute to your monthly cycle.

Why is my period so light? 7 explanations

1. You're stressed

Stress is a normal part of a busy life, but it does take a toll on your body. Dr Lapa explains: "Stress can block the release of hormones that are necessary for normal menstrual periods. When this hormone is blocked, light menstrual periods can occur."

While stress can affect your period, Dr Lapa says daily stresses, such as presentations and deadlines, are unlikely to impact your cycle. Rather, it often takes a one-time, extraordinarily stressful event to create an abnormal period, such as losing a loved one, divorce or illness.

2. You've lost weight

Your body fat percentage and body weight directly affect your period, and being extremely underweight can cause your period to become irregular because your hormones are not working normally. Dr Lapa says: "Low body weight interferes with the production of hormones, which can lead to lighter menstrual periods."

The doctor also adds that losing or gaining an extreme mount of weight can cause irregularities with your period. Be sure to embrace a healthy, balanced diet to ensure your systems are all operating properly.

3. You're getting older

Your age is more than just a number. It can also be a tell-tale sign for different changes happening in your body, including your menstrual cycle. As you approach your mid-30s to early 40s, your ovaries begin to show their age and one of these symptoms could be lighter than usual periods.

Dr Lapa says: "At this age you have fewer functional eggs, and subsequently you may have less estrogen. Your ovaries will officially stop working somewhere in your 50s – with the average age of menopause (defined as your very last period) is between 51 and 52 years old."

4. You're on the pill

One of the most common reasons for having a lighter period is going on the birth control pill, with some doctors prescribing it to people with heavy, painful periods. Dr Lapa explains: "Some birth control methods prevent an egg from releasing in your body. When your body doesn't release an egg, your uterus doesn't create a thick lining, which can result in lighter periods or skipped periods altogether."

Not only does the pill mean lighter periods, but many people experience less severe cramps and more regular periods, which is often a welcome change.

why is my period so light a woman holding her stomach
Rattankun Thongbun

5. You have PCOS

Polycystic Ovary Syndrome, or PCOS, is a fairly common condition in which ovaries become enlarged and contain many fluid-filled sacs which surround the egg. According to the NHS, 1 in 5 women in the UK have PCOS, however not all will show the symptoms.

Dr Lapa says: "When you have polycystic ovaries, the imbalance of hormones can lead to irregular periods, including painful and heavy bleeds, shorter or lighter than usual periods." Some women with PCOS might not even experience periods at all.

6. You've recently had surgery

You'll have been told this when undergoing your procedure, but Dr Datta warns that if you've had any work on your womb or cervix recently, it could certainly affect your period, even if only subtly.

"If you've had recent surgery to your womb or your cervix, for example to treat an abnormal cervical smear, this can also affect your periods initially," she explains. You may expect a lighter flow for a few months. As always, do visit your doctor if you're worried at all.

7. You're over-exercising

Similarly to under-eating, if you're undertaking a significant amount of exercise – that's anything upwards of six workouts a week – you could be putting your body under too much strain and stress, Dr Datta warns. Both emotional and physical stresses can affect your cycle, therefore vigorous exercise can impact your period.

While exercise is good for you, it's the same as everything in life: enjoyed in moderation.

Still worried about your light periods?

Dr Datta recommends keeping a diary tracking your period for at least two to three months to evaluate your symptoms, monitoring your bleeding timings and heaviness. "That way, a doctor will be able to see if there is a pattern to your bleeding and symptoms," she explains.

Do note: if you've missed a period altogether, it's worth reading our guide to what that might mean, and taking a pregnancy test to confirm you're not pregnant.

This article is not intended to be a substitute for professional medical advice or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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