relapse into (something)
To return to a former state or condition after an apparent or partial recovery. The patient relapsed into a psychotic state due to an incorrect prescription of medication. He had been sober for nearly 20 years, but he relapsed into heavy drinking after the death of his daughter.
relapse into something
to experience a return to a worse condition. Valerie relapsed into a coma in the afternoon. Mary relapsed into her depression after a brief period of normalcy.