Guys, I sometimes ride my bike at night in Lagos and there is no such rule, specially for bikes bigger than 125cc. Police target the commercial bikes, aka Okadas, which take passengers for a fee and might cooperate with petty thieves snatching handbags or burglars. They are against these guys circulating at night, although there is no such thing as prison for them. They could face: first the "extraction" of a donation from their daily earnings or second a beating for not cooperating.
Having said the above, I would not circulate on Nigerian roads outside relatively safe town areas by night. It's almost Xmas and highway blocks by armed robbers are rampant. Follow the sun.
Hope it helps.