I've been a computer geek since I was 7 or 8. I started graying at 16. I'm 41 and my hair is completely white now. I wouldn't worry about it. Your only problem will be how first impressions go. But if you accept yourself as you are, it won't hold you back.
I just cut it really short now.
It's like baldness, it is better to accept it with some dignity than look like an insecure dope with a toupee or a comb-over.
One of the signs of serious stress is going bald or having clumps of hair falling out. If you're not at that level, I wouldn't pay much attention to it. But, as always, see a doctor if you're worried.
The patient describes a sudden, asymmetrically presented symptom at an unusual age and exhibits a kind of vague anxiety about it. The patient spontaneously mentions depression and stress to deny that those are issues. The patient offers that perhaps staying up late at night is the primary cause. Unless his or her folks are saying "Oh, yeah, that runs in the family" he or she should have it checked out. He or she should say those things to a doc who can either easily dispel the anxiety or offer some helpful referrals. Geeze.
It's also worth reminding that, in general, HN is not a good source for medical advice (other than "ask a doc"). Several of the comments that I saw when I came back to this thread to see why I might have been downvoted -- are potentially endangering comments. Sure, sure, in some cases even the docs gets stuck and people reasonably fish here for help -- but this ain't that.
The best answer here for someone describing an odd symptom or describing a normal system oddly -- is go find a real life medical professional, don't ask HN.
Please.
If an unusually high-power CRT were to blame, you would have no hair on the left of your head instead of just white hair. Asymmetric UV exposure could bleach parts of your hair.
Not saying it will stop the greying, but it will help you feel great.