I’m 17, and go to boarding school so I’m up late most nights. I get about 6-7 hours of sleep on average. I know that this is not optimum, but will it be noticeably detrimental to my strength gains?
I wouldn’t think so. 4-5 maybe, but 6-7 should be OK.
Why are you up late every day?
Have you considered napping for an hour or two during the day?
As a younger person you probably should be getting a slightly longer sleep than older people, probably more in the 7-9 hour range. But this a very general statement and the amount of sleep that you may actually ‘need’ will depend on your individual needs. So it could be longer or shorter than the generalisation.
In terms of it being detrimental to your strength gains you have to keep in mind that most of your hormone production (and there is a damn lot of it at your age) occurs mostly at night while you are asleep. If you are not getting a good quality or quantity of sleep then there can be problems. There are some good articles floating around the forums on this.
You can probably self assess to see if you are getting enough sleep for your needs. If you are tired or lethargic during the day, if you have poor concentration or trouble remembering things, lack of motivation to do things or are depressed and especially if you feel that if you were put in a dark room at any point during the day and you could just go straight off to sleep, you probably need more sleep. If you do get more sleep and you still feel tired then there may be other medical/physiological problems which may be contributing.