07/26/2022
Choosing the right bulb in your home to achieve better sleep.
The picture here shows the color temperature of LED bulbs at 2700K, 3000K, 4000K and 5000K.
As you can see, the higher the color temperature, the more prominent the blue wavelength light becomes. The shorter wavelengths are a higher power than the longer wavelengths in the visible spectrum, and those wavelengths will dominate what you see during mid-daylight hours.
The human circadian rhythm has been tuned to stages of sunlight over its development. When the Sun beings to rise (and sunset) the higher energy wavelengths are reflected (oblique angles) off the atmosphere whereas the longer visible light penetrates the atmosphere. This is why you have the orange/red visible light appearance at both sunrise and sunset. When the sun starts to move directly overhead, the blue wavelength (9am to 5pm give or take) dominates the visible spectrum over the longer orange/red.
The human body, under normal conditions, will be at its most alert due to the body’s suppression of melatonin when the blue wavelengths are at the highest. As the sun begins to set, and the blue wavelengths are once again reflected off the atmosphere, the human body senses this and starts to increase melatonin levels to get ready for sleep.
If you choose an LED bulb greater than 2700K in your home, the body can still sense the presence of blue wavelengths from the bulbs, further suppressing melatonin production long after the sun has set. This suppression will lead to erratic, poor sleep.
Older incandescent bulbs had very little blue wavelength output.
Phone and electronic manufactures have a night shift mode to block the output of blue wavelength light for this reason.
So, when you are purchasing new bulbs for your home, select the best color temperature for the area of your home to allow for better overall sleep.
Main living areas and bedrooms: 2700K and below.
Bathrooms and other spaces: 2700K and higher.
