All the totally normal reasons why your period is so light

Ally Head, Catriona Harvey-Jenner
·5 min read
Photo credit: Volanthevist - Getty Images
Photo credit: Volanthevist - Getty Images

From Cosmopolitan

If you've ever experienced a particularly light period, you've probably wondered what on earth is going on. Just last month, your period was heavy as you like? Yep, we've been there.

Not all periods were created equal, it seems, and ain't that the truth. Some women get consistently light bleeds, while others are blessed with heavy periods month after month. An assortment, it seems, are treated to a right royal mix up. That is, light some months and heavy some others. Some skip bleeds altogether (but more on that, later).

Being the ever-curious creatures we are, we wanted to know why, exactly, women get light periods, and when it's time to worry.

So what is the definition of a 'light' period? According to INTIMINA gynaecologist doctor Shree Datta, there's no hard and fast rule. A light period is usually 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, so it's also worth considering how heavy your normal periods are to gauge whether your flow is light for you," she adds.

"It's important to remember that your cycle can vary from month to month," she explains. "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 - we've asked doctor Datta and GP doctor Tatiana Lapa to explain why, exactly, a woman has a particularly light period at certain times. It turns out there are various factors which 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 woman’s 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."

But if your period is starting to slow down a bit, don’t freak out that you’re getting old just yet...

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 women 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 women experience less severe cramps and more regular periods, which is often a welcome change.

Photo credit: JGI/Jamie Grill - Getty Images
Photo credit: JGI/Jamie Grill - Getty Images

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 doctor Datta warns that if you've had any work on your womb or cervix recently, it could certainly affect your monthly bleed, 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, doctor 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?

Doctor Datta recommends keeping a diary tracking your period for at least two to three months to evaulate 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 skipped a bleed altogether, it's worth reading our guide to what that might mean, and taking a pregnancy test to confirm you're not pregnant.

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