Do I admit to my boss that I hit a mailbox with a company car because I fell asleep while driving?

I was driving at night three days ago when I very briefly fell asleep while driving a company car and rolled onto the shoulder of the road and hit a mailbox. It was very dark and in the middle of nowhere, and I was a little disoriented so I didn't stop to check the mailbox. I later pulled over to check the car and realized that the passenger side mirror and the right headlight were damaged. I informed my boss of the incident, but I didn't tell her I had fallen asleep while driving. She wants me to help her locate the mailbox to file a police report. What do I do? Do I admit that I hit the mailbox because I fell asleep?

Your boss needs the police report to be able to file an insurance claim and get the vehicle fixed. The insurance is also liable for fixing what you hit. If you tell the the truth, all of the facts will line up with the damage.

When people leave the scene of an accident there's usually a reason. You're going to have to explain the reason for that. If you say you didn't realize you hit something, it will sound like you were drunk. Driving drunk is a crime, falling asleep isn't. I'd tell the truth.