Similar effects on the forward current will happen if the chosen resistor value deviates significantly from the design target value, and tolerances can come into play with either the resistor or nominal LED characteristics. Although there are no absolute rules regarding LED circuit design, all these factors need to be taken into account. For example, as noted earlier, if the total current is increased to try and drive the LEDs harder, higher temperatures at the LED junction is the result. These higher temperatures not only negate relative light output, they can reduce LED reliability and lead to a shorter LED shelf.