I'm going to go against the trend and say that this is one of the short term side effects of being in ketosis. It's definitely happened to me in the past and I know of several others it's happened to. It does pass though!
Yes, reduced sleep is a 'side effect' of ketosis. It's not known why this is (I don't think anyway), but some people believe it is because the brain works more efficiently with ketones as energy and so the body needs less sleep.
Some people find that though they sleep for less time, when they are asleep they sleep better