A Moment of Science gets a chain letter and we discuss the myth behind the whole concept.
If you live in the middle latitudes of the northern hemisphere, the moss will grow thicker on the north side. It may sound like an urban legend, but it’s quite real. And the reason is simple: there’s more sun on one side.
Almost all mammals, in fact, have REM sleep; birds do too, although only in the early parts of their lives. It seems that sleep and REM are required by a particularly complex kind of brain.