Just read this on Wikipedia and thought I would share:
It is principally blue light, around 460 to 480nm, that suppresses melatonin, increasingly with increased light intensity and length of exposure. Until recent history, humans in temperate climates were exposed to few hours of (blue) daylight in the winter; their fires gave predominantly yellow light. Wearing glasses that block blue light in the hours before bedtime may avoid melatonin loss. Kayumov et al. showed that light containing only wavelengths greater than 530 nm does not suppress melatonin in bright-light conditions. Use of blue-blocking goggles the last hours before bedtime has also been advised for people who need to adjust to an earlier bedtime, as melatonin promotes sleepiness.
source: Melatonin - Wikipedia, the free encyclopedia
This might be worth trying out some time, wear safety goggles that block blue wavelengths at night before bed and see if you sleep better