Remember those mood rings everyone had in the nineties? Aquamarine meant you were down in the mouth; grey you were pensive; violet you were aroused. Mine was always a murky brownish navy and I presume everyone else’s was too, given that they cost about £3 apiece so their scientific exactitude couldn’t exactly be counted on.
Want to know a better mood indicator? Your underwear. What do you find yourself reaching for in your knicker drawer on a morning when you’re feeling devious? What do you pull out when you’re planning a seduction? Here’s the science part.