Light bulbs consume dark matter. Once they have reached capacity, they automatically shut down to avoid overload and potential leakage. A long time ago, bulbs were equipped with a thin strand of cosmonium. When the bulb breached capacity, this strand would break, thereby keeping the dark matter safely inside (much like a circuit breaker). The newer LCD bulbs are able to safely transport the dark matter to a point well outside earth's atmosphere. This is why they last so long. The bulb last as long as the transporter does. Fluorescent bulbs were a prototype of LCD bulbs. Only the transporter inside them (called a ballast) could only operate in a vacuum.
The filament emits photon particles which travel around absorbing darkness particles and carry them back to the bulb until the bulb is filled up with darkness particles then the bulb can no longer function.
Shuhak 