Have you ever called in sick because you need a mental health day?

You absolutely can, if it is a colleague that you do not want to say why you are off then simply say "I won't be in today if you could let X person know and I will explain to them when I speak to them" If you have had a recent tough time (this is coming from someone who rarely takes a sick day unless I am dying) is one day going to be enough? Work related stress and sickness can be difficult for you more than your employer simply because one day is likely not to be enough, is there a potential you might be suffering burn out? Approximately 4 years ago I suffered from burnout just one day I just couldn't do it. Did the same as above and told a colleague I would tell my boss the reason when they called. When my boss did call I was honest about how I was feeling, she knew I wasn't one to take the p*ss and to be fair she put in a referral to Occie health and told me to self certify for 7 days. I spoke with Occie health who advised more time off and to see my doctor, I felt like an absolute fraud going to the doctor who offered me 4 weeks off work. I declined this however and asked for a week. He signed me off for 2 weeks however with the understanding that if I felt able to return sooner I could without the need of a fit note, he also told me to call if I didn't feel able to go back after the 2 weeks and would issue another sick note. Occie health also when speaking to them encouraged me to take the full 4 weeks however noted that I declined. They were actually really good from doctor and employer I think this was because it was work induced burn out and my boss knew I was doing the job of 3 people. My concern was that taking too much time off would mean I would struggle to go back so only took an additional week on the doctor's note and went back to it after a lot of talking with myself about work and moving forward. I mean don't expect any kind of let up when you get back, the sh*t kept getting thrown my way once back, things had piled up that other people could have done but left them as usual for me to do but that's another story. If you need to take time for yourself then do. For your one self care