
It all depends on the company, their own pay structure and their client base.
In our company there's wakeovers (awake all night) - dozeovers (awake for most of the night but can sleep when not wanted) and sleepovers where you can sleep for a set amount of time unless there's an emergency. We get paid per hour for wakeovers (£9 ph), but dozeovers and sleepovers are paid per night (£68 and £40 respectively). The sleepovers will be expected to work from 8pm, when the night shift come on duty, until 10pm when they can go to bed and then 7 am until 8am when the day staff come in. The hours either end are not paid on top of the sleepover rate. The dozeovers are expected to work until all the menial duties are done, then they can go to sleep and then be awake if anyone gets up.
I hope this isn't too confusing and is only how the company I work for structure it. Others will differ.
Debs