The adverb intermittently describes something that starts, then stops, then starts up again. If you studied intermittently last night, that means sometimes you studied but sometimes you took breaks to do other things.
If something happens intermittently, it doesn’t happen all the time or in a steady flow, but goes in fits and starts. It might rain intermittently on Monday or your car might intermittently refuse to start. Make sure you spell intermittently with two “t”s. You can blame the Latin for that: intermittently evolved from the Latin root intermittĕre, which means “to cease.”