I get that question asked a lot and here is the answer: It's more complicated than yes or no.

Before you call me out on that, please hear me out.

Red light is the warming spectrum of natural light and can darken melasma temporarily.

Why? 

Melanin needs oxygen to fully develop.

Heat increases the blood flow. More blood flow, more oxygen. More oxygen, more fuel for melanin to go brown.

BUT,...

Receiving more red-light can ease hormonal imbalance (melasma is linked to estrogen dominance).

Red-light can ease oxidative stress from mitochondrial dysfunction (linked to melasma).

Red-light counteracts blue-light overkill from excessive blue-light exposure (blue light causes darker and longer lasting brown spots than UV light does).

Mitochondria are reliant on natural sunlight and respond specifically to red-light. 

And here was a hint. NATURAL sunlight. 

The safest source of red light is natural sunlight.

The Golden Hour is the perfect time to heal mitochondrial dysfunction.

When to catch it? 

During the first hour after sunrise and the last hour before sunset (Golden Hour). The light during the Golden Hour is almost devoid of UV light and has little blue light.
Nature knows best. It’s where we come from and what made us. 

My personal opinion as a trained cosmetic scientist and certified esthetician:

I generally feel reluctant towards man-made devices. 25 years ago, sun beds were all the rage (at least in Europe). Even dermatologists used it. And see how things have changed. I have the premonition the same will happen with red light devices.

So the answer is, if you have melasma, please enjoy the natural red light during sunrise and the sunset as often as you can, aiming for daily.