sleep data

When viewing sleep data, its not very relevant to view it between 0000hrs and 0000hrs, because people usually begin sleep between 2000hrs and 0400hrs for anywhere between 5 and 12 hours. better visualisation would be possible to display the time between 1200hrs and 1200hrs, to not have the sleep slots overflow to the next line.

The cutoff point might be different for different people, and also might be interesting if this were not just 1200hrs but a set-able option. i.e. if you have work at 9am, to easily see how far you sleep in past 7:30am, and what kind of sleep you are getting from that time.

This might also be relevant to be able to set the day-points for other minutised data, not just sleep.