Freeze Dried Blood! Every day the likes of probiotic "good" bacteria in yoghurts, and even the enzymes in washing powder, give us a helping hand. This week we investigate how scientists are designing new ways to protect and guard these tiny helpers, including new techniques to freeze-dry human blood. Plus, news of how sleep boosts learning, the effects of foetal nerve transplants for Parkinson's, tree-hugging koalas and why negative Facebook friends can make you moody. Like this podcast? Please help us by supporting the Naked Scientists