I have had problems sleeping as far back as I can remember and it's gotten to where I don't sleep two to three nights per week, and it's common for me to go 60 hours (e.g., Monday morning to Wednesday night) or more. The longest stint I've gone in the last few years was 134 hours; I got up on Monday and finally fell asleep on Saturday night, but only after I forced the issue by taking some medication. Oddly enough, I felt fine the entire time.

Outside of having some muscle soreness from sitting too long I have never suffered any obvious ill effects either physically or mentally--no cognitive impairment, problems concentrating, memory loss, depression, etc..