Mild mood swings each day are common for everyone but especially those with BP. I get the blank stares often. it's like I have hit a wall and need to recharge to get back to baseline. It is a good idea to withdraw into your room for a while as you recharge and calm down. Staying in there too long might be counterproductive though.

Why this happens, I have no idea. If it is only mild and does not affect your functioning then it is ok but if you are going from hypomania to depression then definitely see your pdoc about it as a med change might help.