My god-father, a chiropractic surgeon, used to use self hypnosis when he wanted to continue to work with little sleep. He would go into a deep relaxed state for anywhere between 20 mins. to an hour, and take a 'power nap'. He'd wake refreshed and alert and ready to continue his work. This does not replace a full night's rest, tho.
It cannot be used too frequently to replace true sleep, but when he needed it, he'd use it.
I do a 'mantra' thing to relax me and see my 'inner mind' and use it to block pain, and also for deep relaxation when I cannot sleep due to pain or discomfort (also when I go to the docs office, to bring my blood pressure down, as I have 'white-coat' syndrome).
It also helps for me to use it, and take a short 'time out' from work when my pain is distracting enough to interfere with my daily activities.