If you don't mind recovering spells, then Heward's Fortifying Bedroll is for you (see Mooncrow's message for book and page).
1 hour of sleep counts as 8.
It does have 2 limits:
1) You can't benefit from it (or another) again for 48 hours, even though the bedroll itself functions 1/day.
2) Any spells you cast in the previous 8 hours count against what you can memorize/spell slots recovered.
And if you want to get technical, sleeping for 1 hour instead of 8 doesn't mean you get to stay up for 23 hours straight without repercusions. Instead, after about 16 hours, you'll be tired and wanting to sleep again, while for the rest of your party, bedtime is still 7 hours away. Kind of like medevil jet lag