Hypnosis is defined as a relaxed, focused state of concentration and hypnosis for sleep is a proven method for combating insomnia.
Hypnosis is really a normal everyday state of mind that we all go in and out of all the time. When you meditate for instance, or are engrossed in a good movie, you are in a state of hypnosis.
You've all heard of the different brain waves that can be measured when we are in different states of mind and here is a quick review:
Beta - This is our normal waking state, alert and conscious.
Alpha - Relaxed, reflecting, or state of hypnosis
Theta - Drowsy, somewhat unaware
Delta - Sleep and all its stages, including dreaming
We actually move around from beta to theta all day long without noticing it. Hypnosis is really just a word to identify a calm, relaxed, and safe state of mind. There is nothing hokey or dangerous about it. So, if you have a problem falling asleep at night you might want to try hypnosis for sleep.
Another word I want to mention is Hypnotherapy. This is the act of a person skilled in hypnotic suggestion (a clinical hypnotherapist) who can walk you through a process to change a behavior. This is only effective if you truly agree to it, and if you do, it works wonders!
If you are interested in trying gentle hypnosis for sleep, check out Wendi Friesen's highly recommended Deep Sleep! Hypnosis for Insomnia. I listen to this all the time and it really does help!