Geezers sleep less than whippersnappers. Everybody knows that, but scientists aren't sure why. A new study from University of California, Berkeley, argues that older people need just as much sleep as younger people, but the degeneration of certain brain signals prevents older people from getting the rest they need. The team was led by Matthew Walker, professor of neuroscience and psychology and head of the Sleep and Neuroimaging Laboratory at Berkeley. Sleep is vital to all animals, says Walker — every single bodily system relies on that downtime to function properly. The Berkeley team reviewed the sleep data of 2 million people and noticed changes in the sleeping patterns over different age ranges. Then they examined the sleeping patterns and neurological impulses of rodents. Walker's team found that the chemical signal that triggers sleep in the brains of mice declines in strength as the mice get older. The brain has a more difficult time receiving the signal as a result, making it