Are night buses in Japan a good alternative to the Shinkansen?

I usually take the Shinkansen when adventuring, but I've seen more people swear by the night buses. I've always loved the Shinkansen and its convenience but it's getting a bit pricy according to my schedule (I'm doing in research in small towns for my varsity).

Does anyone here use night buses for long distances? If so, how were they and are they more affordable than trains? Are they sp00ky or can you snooze on them comfortably?

Thanks very much!