Finding it hard to nod off? Check your calendar. It could be that your period is playing havoc with your sleep pattern.

In fact, up to 70 per cent of women say their sleep changes just before their period. The most common time for this is between three and six days prior, but it can start sooner, and it may last into the first couple of days of your period. This ‘disturbance’ can manifest in several different ways: you may find it harder to get to sleep and/or stay asleep. Or your nights may just be more restless in general. It is known that REM sleep – the deep sleep during which we dream – falls off in this part of the menstrual cycle. So you’ll find you’re not dreaming much either, and a further consequence of that is that you feel sleepy during the day.

Here’s the science. Hormonal changes after ovulation, in the lead-up to your period, affect the body’s temperature control. As progesterone levels fall away, your body temperature rises and inhibits the usual natural drop that happens at night time. This is what affects sleep quality. The shift in temperature is slight, yet significant. (You’ll need a basal body thermometer to detect it – that’s the same thermometer used to predict ovulation.)

So what can you do about it? Keep a diary of your sleeping pattern and if you can see a clear link to your menstrual cycle, you can be prepared for the next one.

In the days after you ovulate, start building your defences by getting plenty of rest – sleep while you can! Do all the usual things that help with sleep naturally, such as cutting down on caffeine and alcohol, staying active, getting plenty of sunlight, and sticking to a healthy diet. Practice a familiar wind-down routine that helps you switch off – read, breathe deeply, drink a chamomile tea, stay away from screens.

Here’s one way to trick your body into feeling sleepy. Keep your bedroom cool, then take a warm bath or shower right before bed. The contrast between the warm bath and the cool bedroom will force your body temperature to drop, and help with sleep onset. If all else fails, simply knowing that the poor sleep will only last a few days should be enough to stave off the anxiety that makes the problem worse.