Format: AbstractJ Pineal Res. 1984;1(2):105-19.
The influence of various irradiances of artificial light, twilight, and moonlight on the suppression of pineal melatonin content in the 🐹 Syrian hamster.
Brainard GC, Richardson BA, Hurlbut EC, Steinlechner S, Matthews SA, Reiter RJ.
AbstractThe purpose of the present studies using artificial light was to determine how the timing and duration of exposure influence the light-induced suppression of pineal melatonin levels in hamsters.
An 8-min exposure to 0.186 microW/cm2 of cool white fluorescent light caused a continued depression of pineal melatonin even when animals were returned to darkness. In addition, the pineal gland does not appear to change its sensitivity to light throughout the night. A 20-min exposure to
0.019 microW/cm2 of cool white fluorescent light did not significantly suppress pineal melatonin during any time of the melatonin peak, whereas a 20-min exposure to
0.186 microW/cm2 was capable of
always suppressing melatonin.
Furthermore, increasing the duration of
0.019-microW/cm2 exposure to 30, 60, 120, or 180 min
does not increase the capacity of this irradiance to depress melatonin. 👍 Similar to artifical light, natural light has a variable capacity for suppressing nocturnal levels of pineal melatonin. Twilight irradiances of
0.138 microW/cm2 or less did not suppress nocturnal melatonin whereas twilight irradiances of 3.0 microW/cm2 or greater did suppress pineal melatonin. A few animals did have lower melatonin after a 40-min exposure to full moonlight during July (0.045 microW/cm2) or January (0.240 microW/cm2).
However, pineal melatonin levels remained high in the majority of animals exposed to full moonlight. 👍
PMID: 6545810
[Indexed for MEDLINE]
https://www.ncbi.nlm.nih.gov/pubmed/6545810Agelbert NOTE: In regard to light mediated melatonin production or suppression, we are just like hamsters. If you wish to avoid suppressing your melatonin levels at night, you need to get some sort of night lighting that lacks blue wavelengths. Regular electric lighting in your home contains blue light. Blue light will trigger melatonin supppression, which will degrade the quality of your sleep. 👎
For better sleep, you need to avoid the wavelengths that do not trigger melatonin suppression. A night light with little or no blue light is the way to go. 🌜👍
Nobody sells lights by microwatt/square centimeter ratings, so the above study does not help in shopping for these lights. Also, searching for lights by lux level (light
intensity) is not the way to shop for these lights either. In the above study, the unit they used (microwatt/square centimeter)
is a measure of energy absorbed, which converts to lux poorly because there is a lux (light intensity,
not energy absorbed) formula for microwatt/square centimeter to lux
for every wave length in the light spectrum.
So, rather than try to shop for LED lights by lux, just search for LEDs without blue light (380nm to 500nm wavelength). You need blue light when you are awake. It helps you remain alert. But, blue light triggers the suppresion of melatonin production. So, you need to avoid blue light when you want to sleep.
Below is an example of products you can buy to eliminate blue light in your home at night. I've never bought anything from them. I just found them with a quick search. I'm sure there are many other places to buy products like these: