Regarding involving HR, always remember what their job is: they exist to protect the company from the employees.
If that involves keeping you safe (so you don't die and cost them money when they replace you/pay compensation to your surviving family/pay fines to the government) that's good for you. If it involves making sure compensation flows to your bank account properly so you continue to show up at work, that's good for you. If it involves throwing a holiday bash to keep the masses happy and productive, that's good for you.
If it involves pushing you out of the company because you're potentially a nutter that needs them to pay for time off/mental well being services/etc, well, guess where you end up.
At least on the LHS of the Atlantic...