This is my experience, i was sleeping in my desk when i worked because i was very tired. How about you guys?
I would say that sometimes i may feel a little tired but never have have fallen a sleep on the job,as i work from home and have done for many years i usually only work about 3-4 hours a day anyway so i can rest as and when i want too.
I have yet to sleep on the job, but there have been moments where I found myself slightly nodding off.