Manager told me Mental Health issues aren’t a real reason to call in sick.

What’s everyone’s thoughts on this? I called in sick yesterday as i physically could not bring myself to leave my bed all day so i called in sick, today i came into work and my manager who i thought i could trust asked me why i called in sick…. Stupidly i told him my reason only for him to tell me Mental Health is not a real reason for using up a sick day.