Is it better to leave a light on or turn it off then back on when you are only gone for about five minutes?

It is better to turn it off, the start up current in a light bulb will never exceed the power consumption over a five minute period. A motor shouldn't even be left on for that same reason. (Yes there is a start up current in a light bulb, it's just extremely small.) Your bulb will last longer if you leave it ON. Its the on/off cycle that kills bulbs. Electricity wise; you may save a few pennies a month by shutting it off. True, bulbs do loose life if constantley turned on and off, but you would have to turn it on and off hundreds of times for this to be an issue. A more serious issue would be where the bulb is located,for example a light bulb next to a door will not last as long as a light bulb in the middle of the room, simply because of the shock from the door closing. It is still best to turn the light off, esspecially if its a long life bulb.