So basically, periods ruin our lives in every way. We already knew that we could thank TOM for our monthly break outs, chocolate binges and ugly cry sessions. But we didn't know the fecker was responsible for our bad hair days too?! According to science, we actually suffer a bad hair WEEK in the 7 days running up to our period. We're talking extra oily, extra lank, extra stringy - basically Worzel Gummidge. According to the app that allows you to track your cycle, Clue, users report that their hair looks more “oily,” “flat,” and “stringy” starting a week before their period. And it's not all in their heads so to speak; the sciency bit backs this up. New York dermatologist, Whitney Bowe tells Women's Health:  "In the week leading up to your period, progesterone levels soar. The hormone triggers sebum production—which means your skin pumps out more oil—and while this increases oiliness on your complexion, it also increases oiliness on the scalp. The hormone triggers sebum production—which means your skin pumps out more oil—and while this increases oiliness on your complexion, it also increases oiliness on the scalp." Devo.