Syllable division derived from spelling — this word is not in the pronouncing dictionary, so no phonetic transcription is shown rather than a guessed one.
sleep-learning is a noun meaning "teaching during sleep (as by using recordings to teach a foreign language to someone who is asleep)". It carries one recorded sense.
teaching during sleep (as by using recordings to teach a foreign language to someone who is asleep)
Definitions, synonyms and semantic relations for sleep-learning come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.