Deep Sleep, goes into Comma

My iphone 4 has suddenly started to go into comma, yes Deep sleep issues. If I put it in Sleep mode, after around 10 mins it will go into comma and wont wake up. then I after to press and hold power+sleep, after serveral tries, from 10 to 50 sometimes, it will wake up..

but i noticed if I have it plugged to the charging, it won't go into the Deep sleep, and will wake up normally.. the moment you take it out of charge, and put it to sleep for more than 5-6 mins, it won't wake up

Can u provide me with a repair pls ??

Gagan

mehargags@hotmail.com