DD is almost 10 and she has a set bedtime of 8.30, no changing it! She knows that if there are any issues with her not getting up in the mornings then she goes to bed 30 minutes earlier, so she is usually up around 6, but can sometimes sleep until 7.30am, which is still fine!
The older girls are 18 and 21, well, they can be up all night, they are adults now, its their problem if they don't get up on time!