I was thinking if there is a way that i can go about making my screen go black automatically for about 10seconds, (with a message like "take a break" printed on the screen) and after 10seconds everything comes back to normal....
is there any way that i can do this...???

to further clarify the question...

suppose now the time is 10:00am
i start my "take-a-break.sh" or "take-a-break.o"(yes, c program idea is also welcome) program...

at 10:10:00am the computer screen should go black(or Locked),with a message -"take a 10sec break"(optional) and at 10:10:10am the screen where i was working should come back(or UnLocked) automatically...

again at 10:20:10am the process would repeat , then again at 10:30:20am....and so on...

this is for my eyes...i keep forgetting the i should be taking 10sec break and see into a distance every 10mins for about 10secs to relax my eyes...(everyone else,working on a pc, should also do this...)

any ideas?

well,yes,i could configure my screensaver to lock-up my screen every 10mins...but how would i be able to make the screensaver go away automatically after 10seconds?