On my EM rotation we probably averaged at least suicidal ideation per shift. Psych has to go see them regardless of when it happens.
I think many/most residencies have transitioned to a night float anyway, so all it means is you just sleep during the day instead.
Are you a premed? If so, you should seriously consider psychology. You'll have a nice lifestyle, save a lot of time/money, and actually work at cheering people up by talking to them. The patients you will see as a psychiatrist are well beyond this, and you will find you cannot have a meaningful conversation with many of the patients you will see, particularly on inpatient.