Do sodium lights repel gnats

Yes, sodium lights repel gnats.

Specifically, the term in question designates biting midges, fruit fly-like flies, gnats and midges. All of the above-mentioned insects have shared preferences for bright lights. Not one of them holds the same propensity for the sodium bulb's dimmer, more orange light. If their favorite food source of decaying material or waterlogged mulch is abundantly around, then dimmer lights will have the effect of repelling some -- but not all -- feeding-minded gnats.