lapse into

phrasal verb

lapsed into; lapsing into; lapses into

1

: to begin using or doing (something that should be avoided) for a short period of time

He's a good writer, but he occasionally lapses into jargon.

2

: to begin to be in (a worse or less active state or condition)

The crowd lapsed into silence.

The patient lapsed into a coma.

The society lapsed into decline.