Yes, Mr R., laptop.
In my (admittedly limited) experience, you have trouble with the ribbon cable to the screen. Hopefully it's just one of the terminations becoming, er, unterminated.
Symptoms suggest a 'manual diagnostics test': i.e. move the screen up & down, preferably without actually getting to the point where the machine tries to sleep. See if it gets better or worse. If it does make a difference, you may try a repair:
Goog for a service manual online, if you are nervous about the next bit.
You should be able to get to the 'onboard' end of the ribbon cable by removing the keyboard - probably by undoing about half a doz screws underneath & carefully lifting bits away. But the manual will tell you.
Sod's law, of course says that if it's the terminations it'll be the one behind the screen.
Or it could be the ribbon cable itself... usually you can find one for £10 -20 on Ebay. (model specific, of course.)