Menstrual phase: what happens, how you may feel, and what helps

Key takeaways

• The first day of your period is day 1 of your cycle.
• Most periods last 2 to 7 days, with about 1 to 5 tablespoons of blood lost in total.
• Heat and gentle movement may ease cramps.
• Iron-rich foods help replace what you lose, especially if your periods are heavy.
• Very heavy bleeding or severe pain is a reason to see a doctor.

The menstrual phase at a glance

What happens in the menstrual phase?

If you did not get pregnant in your last cycle, estrogen and progesterone drop and the lining of your womb comes away. That lining leaves your body as your period. The first day of bleeding is day 1 of your cycle, and your ovaries are already preparing the next egg.

Doctors count these days as the start of the follicular phase. Cycle syncing gives them their own name because they often feel so different from the days that follow. Over a whole period you will usually lose about 20 to 90 ml of blood, which is about 1 to 5 tablespoons.¹ It often looks like more than it is.

How long does the menstrual phase last?

A period can last between 2 and 7 days, and it usually lasts about 5.¹ Bleeding for more than 7 days is one sign of heavy periods, so mention it to your doctor if it happens often.³

How may I feel during my period?

Many women feel more tired and want to slow down. Cramps are common, and period pain usually lasts up to 3 days.² Some women also notice a lower mood or poorer sleep, while others feel lighter once premenstrual symptoms ease.

Cramps happen because your womb tightens during your period. You may feel them as a sharp pain or a dull ache in your lower tummy, and they can spread to your back and thighs.² How you feel can change from month to month, which is why tracking a few cycles is useful.

What should I eat during my period?

Focus on warm, regular meals with iron-rich foods, because you lose some iron with every period. Good sources include red meat, beans, lentils, chickpeas, dark green leafy vegetables, dried fruit and fortified cereals. Eating plant sources with a vitamin C food, like peppers, citrus or berries, may help you absorb more.

Heavy periods are one of the most common causes of iron deficiency anemia, which can leave you tired, short of breath and paler than usual.⁴ Large amounts of tea and coffee can make it harder for your body to absorb iron,⁴ so try having them between meals rather than with them.

Warm food is not proven to ease cramps, but many women find it comforting, and comfort counts on hard days. Do not start iron tablets on your own. If you think you may be low, ask your doctor about a simple blood test.

Should I exercise on my period?

Yes, if you feel like it. Gentle movement such as walking, yoga, swimming or cycling may ease cramps, and you do not need to stop your usual training. On heavy or painful days, it is fine to go lighter.

The NHS suggests gentle exercise as one way to manage period pain.² A Cochrane review also found that regular exercise, done about three times a week across the whole month, may reduce period pain, although the evidence was low quality.⁵ Research on whether strength or speed drops during your period shows only small, varied effects, so let your energy guide you. Our guide to cycle syncing explains what the studies say.

How can I sleep better during my period?

Some women sleep worse during their period, especially if they have painful cramps.⁶ A warm bath before bed, a heat pad or hot water bottle for cramps, and a regular bedtime may help you settle.²

Wrap a hot water bottle in a towel so it does not burn your skin. If pain wakes you at night, ask your doctor or pharmacist about pain relief that suits you. An earlier night on your heaviest days is a small change that can make the next day easier.

How should I plan work during my period?

If you can, keep this week a little lighter. Many women use the menstrual phase to review, plan and tidy up loose ends, then save big launches or tough meetings for later in the cycle. There is no rule, so plan around how you actually feel.

Small things help: block a quiet hour in your calendar, say no to optional extras, and keep pain relief and period products in your bag. Regime Longevity shows your predicted period and phases, and your daily plan adjusts work, food, training and sleep to them, so these days do not catch you off guard.

When should I see a doctor about my period?

See a doctor if your periods are very heavy, last more than 7 days, or are so painful that they stop you doing everyday things. Ask for an urgent appointment if your pain is severe or worse than usual and painkillers have not helped.²

Signs that your periods may be heavy include:³

• Changing your pad or tampon every 1 to 2 hours.
• Needing to use two types of period product together.
• Passing blood clots larger than about 2.5 cm.
• Bleeding through to your clothes or bedding.
• Feeling tired or short of breath a lot.

Also see a doctor if you bleed between periods or after sex, or if your periods become more painful, heavier or irregular.² Heavy or painful periods are common, and there are treatments that can help, so you do not have to just put up with them.

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