Glen Jeffery, University College London 

Sunlight. Don't look directly, of course. But spend as much time outdoors as possible. Melatonin is replenished within the mitochondria during daytime with longer wavelengths. And flame light (candles etc.) in the evenings less likely to trigger the melatonin suppression, also gives out lots around the red region.

The question was where can you buy one....Amazon, 25 bucks with a spacer. Sunlight yes, but ONLY in the very early morning before 10am.

@@melodymerritt8419 You're right, why use the sun for free when you can buy an artificial and frequency-deficient source? Sunlight is just too inconvenient. Or perhaps it might just happen to be inconveniently irreplaceable?

hi you can now get a pair of glasses

hi you can get a new pair of glasses which have been recommended by Professor Jeffery which are not too expensive which use 670 nm light see dreamoptics