YOU SAID:

There was a mouse in my bed when I went to sleep

INTO JAPANESE

寝たとき、ベッドにネズミがいました

BACK INTO ENGLISH

There was a mouse in the bed when I went to bed

INTO JAPANESE

私が寝たとき、ベッドにネズミがいました

BACK INTO ENGLISH

There was a mouse in the bed when I slept

INTO JAPANESE

私が寝たとき、ベッドにネズミがいました

BACK INTO ENGLISH

There was a mouse in the bed when I slept