How long before sleep depravation causes total insanity?

I've managed an average of 4 hours sleep for the last 3 nights. I didn't get home from Denver until after 9:30 PM and still had coop orders to fill for delivery to the drop off site this morning. So after getting to bed after Midnight I was up again at 5:30AM to get things organized for the Coop's trip to Denver with orders to be delivered today. The bass drum is still announcing the upcoming parade with the furnace in the lead position. Something will definitely need to be done about that. I am taking a sleeping pill tonight and going to bed early. Hopefully I'll get right to sleep and not wake up until the sun comes up tomorrow.