To be or not to be in pyjamas when going to bed is an individual choice. But is it true that we sleep better when we're naked, as some people claim? "To generalize and say that sleeping naked equals a better, deeper sleep - you can't really do that," says psychologist Markus B. Specht, who heads a sleep medicine clinic in Germany. And yet it whether you sleep with or without clothes can still make a difference, Specht explains to us, giving tips on hygienic bedtime habits. Opinions on sleeping n