Brain Strain (side effect)

Remember that episode on Spongebob where his brain was overwhelmed and it caught on fire, that's how brain strain feels. The amount our brains have to deal with is incredible to me, performing numerous task constantly and daily. Overthinking is just another huge package to sort out and deal with, in other words it will increase the mental activity of the brain and cause it to strain. This is why they say don't think about anything if you have a headache or don't think to much or you might get a headache.