The translation "Better sleep at home" carries a suggestive meaning as in "it would be better for you if you were to sleep at home". Is this what the Russian sentence "лучше спать дома" also conveys? And in that case is the translation "sleeping at home is better" not accurate?
These hints are designed to cover a variety of possible contexts, but "better than" doesn't fit into this particular sentence, even though it could fit in a more detailed version:
Лучше спать дома = [it's] better [to] sleep at home
Лучше спать дома, чем на улице = better sleep at home than outside (or literally "in a street")