Woman looking out of a plane window

Does flying affect your menstrual cycle? How crossing time zones can affect your period

Posted by for Wellbeing

Ever flown overseas only to be surprised by an out of sync period? You’re not the only one – frequent flyer and writer Lisa Bowman looks into how and why travelling affects our menstrual cycles. 

I flew from the UK to India in 2014 and despite being mid-cycle, I got my period the day after I landed, which caught me off guard. Two months later, I flew to Sri Lanka (the same time zone as India) and my period came a few days after landing. Nine weeks later, I flew to Australia, and it happened again – my cycle was all over the place.

When I asked my friends if this had happened to them, I received multiple stories about cycles going haywire and periods becoming heavier/lighter/more painful – or completely stopping – while travelling. So, why is this? 

It turns out our menstrual cycle is closely linked to our circadian rhythm, ie the body’s internal 24-hour clock.

‘Most of the processes in our body are controlled by hormones, which are little messengers going from one place to another to change functions,” explains Dr Gareth Nye, physiology lecturer at the University of Chester.

“Many of these hormones are under the influence of the circadian rhythm – these are physical, mental and behavioural changes that follow a 24-hour cycle eg waking up/going to sleep. Though the menstrual cycle is circalunar (monthly) it’s also impacted by the circadian rhythm.”  

Crossing time zones in a short space of time causes jet lag, which is when our body’s circadian rhythm no longer matches the external environment. So, if you fly from London to Sydney (which is currently 10 hours ahead of GMT), your body will think it’s bedtime when it’s actually breakfast. Jet lag itself usually only lasts a few days as you adjust to the new time zone, but has knock on effects across the body.

“Normally, changes over two time zones is sufficient to have an impact,” says Nye,

“This causes problems for the whole body and has been shown to impact our brain, heart and metabolism. During your period, the body temperature rises and other hormone cycles are put out of line, which is why many women experience irritability and disrupted sleep. When you add in the impact of jet lag, the combination is enough to affect the whole menstrual period.” 

The more you travel, the more your cycle may be disrupted

Last year, Ruby Brewer flew from the UK to Costa Rica and got her period unexpectedly on the flight.

“Then, for the three months I was in Costa Rica, my periods completely stopped,” Brewer says.

“They slowly adjusted to normal once I got home, but then I flew to Sri Lanka six months later, and despite being due on, I only had one spot of blood, then nothing else for the two months I was away. When I landed back in the UK, I got my period two days later, but it took a while to get back to normal.”

Thanh Nguyen – a former air steward – also found that frequent flying negatively impacted her period: “I was a flight attendant for four years and can confirm that my menstrual cycles were utterly ruined as I crossed different time zones every day. I haven’t flown for three years now, but my menstrual cycles are still unstable.” 

Moon cup pattern
Anecdotally, lots of women have experienced random periods, missing periods and weird spotting after travelling long haul.

Unfortunately, it seems that the more you travel, the longer it takes for your cycle to find its rhythm again.

“A 2013 study of 43 flight attendants showed 21% of the study group experienced irregular menstrual cycles,” explains Nye.

“It occurred more frequently in women whose length of work exceeded five years and in women covering more than 14 routes a week, though the results were not conclusive.

“It also revealed that women with sleep disturbances complained of period changes significantly more frequently, indicating that the changes in cycle are affecting sleep.” 

Stress can also impact periods

Travelling is often stressful – especially post-Covid with rules and regulations constantly changing – which can add to your womb woes.

Stress (whether internal or external) raises cortisol,” explains Dr Nicky Keay, an endocrinologist at Forth With Life.

“Lack of diurnal variation disrupts the hypothalamic-pituitary axis, causing downregulation – essentially, signals to the ovaries are disrupted, causing irregular periods.” 

How can you prevent menstrual cycle disruption when travelling?

Unfortunately, there’s not much we can do to prevent our periods from going haywire when travelling.

“Try to avoid frequent long haul flights,” advises Keay. “However, if this is part of your job, then sometimes taking a combined oral contraceptive pill might help as this switches off female hormone fluctuations.”

You can also do your best to beat jet lag by setting your clock to your new time zone as soon as you get on the flight, sleeping as much as possible on the plane if it’s a night flight, and making sure you switch meal times and bedtime to your new time zone as soon as you land (no sneaky daytime naps!).

However, whether your cycle is affected by travelling is the luck of the biological draw. 

“Every woman’s menstrual cycle timing, level of hormones and biological response to hormones is individual to her,” Keay explains.

“This is why two women’s hormone networks will respond differently to the same flight. It also depends when in the cycle travel occurs.”

Using a period tracking app – I use Clue – is really useful for spotting any irregularities. If you usually use a period tracker as contraception, it’s safer to use condoms until your cycle settles, as you won’t know when your ‘fertile window’ is. It’s also wise to keep period products on you at all times, just in case.

You know your body better than anyone, so if you’re concerned about anything to do with your cycle, speak to your GP. 

Image: Getty

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