Sober:

I stayed up for 4 days straight last summer. By the end of it I was very sick, felt like I was drunk, couldn't keep my eyes straight, and even began to have mild hallucinations (the walls seemed to be made of water, the floor was breathing, etc.)

Intoxicated:

I stayed up for two days high on ecstasy and marijuana, by the end of the second day I had a monster back ache, was seeing windows in the sides of McDonald's that didn't exist, experiencing severe anxiety, afraid I would be high for the rest of my life, the inside of my mouth was chewed to pieces, my jaw was clenched shut, and I was convinced a map to a sexual health clinic was a map to my destiny.

I don't recommend staying up for more than 18 hours to ANYONE.