YOU SAID:

I went to sleep at twelve thirty am

INTO JAPANESE

午前12時30分に寝ました

BACK INTO ENGLISH

I slept at 12:30 am

INTO JAPANESE

私は午前12時30分に寝ました

BACK INTO ENGLISH

I slept at 12:30

INTO JAPANESE

私は12:30に寝ました

BACK INTO ENGLISH

I slept at 12:30