Exodus 13:21

The (presence of the) Lord was going before them by day in a pillar (column) of a cloud to lead them along the way, and in a pillar of fire by night to give them light, so that they could travel by day and by night. 

When we fellowship with God and spend time in the Word and His presence, we open ourselves up to His leadership in our lives.  The light of God through the Holy Spirit is the light that will guide us both night and day.  The devil knows this, and it is why he wants to distract us with time wasters that draw us away from our God time.