It can be due to digital eye strain , refractive error( means probably you need glasses) in that case do you feel any blurring of vision at the same time or any headaches. If yes when did you get your glasses checked last time?
And one reason could also be raised intraocular Pressure.
For digital eye strain - you can probably follow 20-20-20 rule - where you can just see at an object which is 20 feet far, for 20 sec every 20 minutes while you work on your laptop or do any of the screen work. Or simply close your eyes and look away from the screen for 20 secs every 20 minutes.
And take enough sleep of atleast 6-7 hours , avoid night time screen use like mobile phones , laptop , etc, even if you do use screen please decrease the brightness of your screen according the the brightness of your surrounding area where you are working
and take a proper diet with increase intake of water and decreased intake of caffeine if possible .
For refractive error - please get your glasses checked if you did not get it checked in last 6 months. For that visit your nearby eye hospital.
For raised intraocular Pressure - you should consult your nearby ophthalmologist please.
Thank you.
Next Steps
First try to do what I told for digital eye strain for atleast 2 weeks . If that's not helpful try to visit your nearby Ophthalmologist for further checkup please.