I don't really agree with setting arbitrary sleep durations since they can add to the pressure many people put on themselves to get the 'right' amount of sleep.
I do, however, pass on recommendations that I come across during the course of my research as I know that many people are interested in knowing whether or not they are getting enough sleep.
When it comes to teenagers and sleep, new research has suggested that teenagers should be getting between 7.5 and 8.5 hours of sleep each night in order to maintain optimal levels of blood sugar and insulin (remember the link between insomnia and diabetes).
It's worth mentioning that for the purposes of this study, researchers looked at 62 obese teenagers with an average age of 14, and that the teenagers were only monitored for 36 hours.
Still, since we already know that sleep deprivation and diabetes are linked, it's worth paying extra attention to make sure your teen is getting enough sleep.
Source: Diabetes Care