How "springing forward" affects your menstrual cycle

Research suggests that women’s internal body clocks tend to run slightly earlier than men’s, meaning even a one-hour time change may have a greater impact on women’s sleep and circadian rhythm than it does for men.

With the clocks recently going forward by an hour, we spoke to Dr. Charis Chambers, Clue’s Chief Medical Officer, to help interpret what current evidence suggests about the impact of Daylight Saving Time (DST) on women’s health and menstrual cycles. She also shares advice for those who notice changes in their cycle or mood during this transition.

Key takeaways:

• Your internal body clock (circadian rhythm) influences the daily fluctuations in estrogen, LH, and FSH

• Research suggests women’s body clocks tend to run slightly earlier than men’s, which may influence how they respond to time shifts

• Circadian disruption is linked to irregular periods and can worsen mood symptoms, including PMDD

• During perimenopause, fluctuating estradiol can affect circadian rhythms, which may increase sensitivity to changes in light and sleep patterns

• Less daylight can shift melatonin timing and influence cortisol rhythms, which may affect your daily energy levels

1. Why might women be more sensitive to the disruption of the clocks changing?

Women may be more affected than men when the clocks go back in the fall or forward in spring, because their internal body clocks (circadian rhythms), hormone levels, and menstrual cycles are more closely connected. 

Research shows that women’s body clocks are naturally set earlier than men’s, even when they go to bed and wake up at the same time. Women also tend to wake up earlier and prefer mornings more than men. Because of this, even a 1-hour change in time can throw off women’s sleep, alertness, and overall body rhythm more than it does for men.

There’s also evidence that changes in natural light and timing, like those that happen with seasons, can affect women’s reproductive health and menstrual cycles. For example, more daylight and sunshine are linked to shorter cycles and higher chances of ovulation. 

Daylight Saving Time (DST) changes the timing of light exposure, which might have some effect, but the 1-hour change from DST is much smaller than the shifts caused by seasonal changes.

2. What symptoms might women notice during clock changes?

Around daylight saving time transitions, women may experience sleep disturbances, increased menstrual symptoms, mood changes, and possible menstrual cycle irregularity due to circadian rhythm disruption.

3. How do circadian rhythms interact with the menstrual cycle, and why might changes in sleep or light exposure affect mood, energy, or cycle symptoms?

A woman's circadian rhythm and her menstrual cycle are closely linked. Changes in sleep habits or light exposure (like staying up late, working night shifts, or getting less sunlight) can affect mood, energy, and menstrual symptoms because of how hormones and body systems interact.

The brain's internal clock controls daily hormone patterns, including those involved in the menstrual cycle. Hormones like estrogen, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH) naturally follow a 24-hour rhythm, even without light cues. Estrogen also directly affects the body’s internal clock.

Different phases of the menstrual cycle can affect your body clock and sleep patterns. For instance, during the luteal phase (the second half of the cycle), body temperature rises, and normal rhythms of hormones like melatonin and cortisol weaken.

This phase often brings more daytime sleepiness, less deep sleep (REM), and worse sleep quality, especially around a woman’s period.

When the body clock gets thrown off (by poor sleep, shift work, or irregular light exposure), it can make menstrual symptoms worse. This could include irregular periods, heavier bleeding, more pain, bloating, and mood swings.

Women with severe premenstrual mood issues (like PMDD) often have disrupted melatonin rhythms and feel worse emotionally in the second half of their cycle.

4. As daylight reduces and melatonin production increases earlier in the evening, how might this affect estrogen, progesterone, or cortisol patterns in women?

When there’s less daylight, like in autumn and winter, the body produces melatonin earlier and for a longer time. This can lower estrogen levels, increase progesterone, and reduce the strength of daily cortisol rhythms.

These hormone changes are more noticeable when estrogen is already low and can vary depending on a woman’s age and where she is in her menstrual cycle. As a result, women may experience changes in mood, energy, and menstrual symptoms during the darker months.

5. Do you think our modern lifestyle (e.g., screen time) amplifies the biological impact of clock changes?

Spending more time on screens, especially in the evening, can make the effects of clock changes worse. This is because screens give off artificial light, especially blue light, which delays the body’s release of melatonin (the sleep hormone), throws off the internal clock, and leads to shorter, lower-quality sleep.

Women may be more affected by this because their bodies are more sensitive to changes in their internal rhythms and hormones.

Using screens at night can increase the delay in the sleep-wake cycle caused by time changes, leading to more fatigue, low mood, and less energy. People who naturally stay up later are especially vulnerable, since their body clocks are already more sensitive to light-related disruptions.

6. Are women in perimenopause or menopause more sensitive to seasonal clock changes due to already fluctuating sleep and temperature regulation?

Those experiencing (peri)menopause may be more affected by seasonal clock changes, like daylight saving time, because they’re already dealing with sleep problems and temperature changes caused by shifting hormone levels.

Lower estrogen (estradiol) and higher FSH levels during this time are linked to more frequent night awakenings and disrupted sleep, even without hot flashes or mood changes. These hormonal changes interfere with the brain’s ability to regulate sleep, body temperature, and the internal body clock, making sleep more disrupted and body temperature less stable.

For people experiencing (peri)menopause, their sleep and circadian rhythms are already more fragile. So time changes, like daylight saving time, can make things worse.

7. What advice would you give women who notice their cycles or mood feeling 'off' as the seasons shift, and when should they seek medical help?

If you notice changes in your mood or menstrual cycle as the seasons change, it’s a good idea to track your symptoms for at least two cycles using an app, like Clue. 

This can help you figure out if there’s a pattern or if it might be something new or concerning. Tracking also makes it easier to talk to your healthcare provider if you need help.

For mild symptoms, healthy habits like regular exercise, spending more time in natural light, and improving your diet can help. If symptoms are more severe or don’t go away, treatments like cognitive behavioral therapy (CBT) or certain antidepressants may be effective. 

Light therapy can also help if your mood tends to get worse in the darker months, as with seasonal affective disorder.

You should see a healthcare provider if:

• Your symptoms are seriously affecting your daily life

• You have symptoms all month long (not just before your period)

• You have unusual bleeding, no periods for over 3 months, or new irregular periods—especially if you're a teenager or under 40, since this could be a sign of something like early menopause or another health issue

Women experiencing (peri)menopause who are dealing with major mood swings, depression, or trouble sleeping should get personalized medical care.

These symptoms are common during this stage of life and often need treatment, which might include hormone therapy, antidepressants, or other non-drug options based on what works best for the individual.