Alien Sleep Cycle May Be a Problem!

Whenever the subject about aliens appears, especially in movies, the main concern is always whether or not they are hostile or not. But there's other things to consider.

Imagine aliens live on a planet where their day has 56 hours, and then they land here. If they adapted biologically to their planet, like humans did, and sleep in intervals of 56 hours, NOT like humans do, it would be a major problem if they where to live among us.

I don't care how friendly they are; if their sleep cycle is once in 56 hours i don't want to be living near them, no matter how awesome it would be!