Interestingly most Psych units I’ve worked (US) serve (roughly timed):

0800 - breakfast

• along with a lightly caffeinated coffee or tea, the only caffeine routinely served

1200 - lunch

1700 - dinner

2000 - snack

• usually prepackaged chips and crackers, sometimes cookies or ice cream. The long stay hospital gave the patients 25¢ for every group they attended and they could order nicer stuff from the staff member who made the weekly Walmart trip.