The pineal gland isn't protected by the blood brain barrier: it will accumulate halides like fluoride and bromide, as well as heavy metals like mercury. It's actually the organ who accumulates the most fluoride. And thus won't be able to secrete melatonin as it should.
Iodine detoxifies the pineal gland and allows it to secrete normally melatonin. It will inactivate the mercury and replace the fluoride and bromide.
Not that it's a spot effect either.
Like people saying take magnesium before sleep...
What matters is how much iodine or magnesium has accumulated in your body to reach adequate levels and exert its effects.
Taking it morning or before bed doesn't make a difference on how well you'll sleep, save the placebo effect