Iphone 4 turns off

[xRYD3Rx]

Every day when i go to sleep i put my iphone on the table "turned on"
When i wake up i press the home button the screen doesnt turn on its all black like its turned off, then i have to hold them home/power button for like 10-20 second for it to turn on ! Is anyone having this problem ? Any fixes ?

 

[jbcraigs]

Have u checked that this is not because it is running out of battery? When you turn it on, how much battery charge do u see?