It's one of those suggested techniques that may improve trichome and terps by like 2/5% just like ice water in the last week but there is not enough evidence around to support it. But it does kinda make sense although the benefit would be minimal 🌱👍
Some fact in it, its best to harvest the plant before she wakes up from sleep so a short dark period is not a bad idea but this can be say 6 hours it doesn't have to be days of dark hours.