A black line/spot on the white part of my eye, what could it mean?

I just noticed this today but I found out that I have a black line or some sort of spot on the white part of the eye. I have been going nuts about it and was afraid that it’ll affect me for the long-term. Any eye doctors out there, please let me know anything that may be the case. P. S My parents told me to not worry about it and said that it might be due to not sleeping much and looking at screens in the dark, which is one of the habits I’m trying to fix recently.

A black line/spot on the white part of my eye, what could it mean?
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