Paper Dolls or the Heimlich, the Zipper or the Cliffhanger - how do you and your partner share a bed?Pictures taken from The Secret Language Of Sleep: A Couple's Guide To The 39 Positions, by Evany Thomas and Amelia Bauer, published on 1 February by ­McSweeney's at £12.99. To order a copy for £11.99, with free UK p&p, go to guardian.co.uk/bookshop or call 0330 333 6846.