Fuddled
/ˈfʌdld/
Definition 1 of 1
Pro Tip 1/3Alcohol Related
Primarily used to describe confusion caused by drinking too much alcohol. 
After several shots, his thoughts were completely fuddled.
Pro Tip 2/3Mental Clarity
Can describe someone's state when they can't think straight, even not related to alcohol. 
She was so fuddled by the complex math problem that she gave up.
Pro Tip 3/3Colloquial Usage
It's a casual word, so it's not suitable for formal writing or speaking. 
I wouldn't tell my boss I'm fuddled; I'd say 'I'm having trouble focusing'.