Most people spend around a third of their lives asleep, and yet we know almost nothing about what goes on in the land of nod. So this week we're going "under the covers" to investigate the science of sleeping including hearing from sleep talkers, probing the world of lucid dreaming and finding out what sleep deprivation does to the brain. Plus, in the news, the missing Beagle 2 probe is pinpointed, how the ingredients for life on Earth could have been cooked up in comets, and the computer that knows you better than your best friend...