If you'd prefer an in-depth explanation of lighting and its effect on our physiology (sleep included!), you can read our article about light and health here. Otherwise, read on for a quick summary on light and sleep!

We always say that light can control much of our day-to-day lives, dictating how alert we feel but also how well we sleep. 

So, how exactly does light affect our sleep?

It all comes down to our circadian rhythm, controlled by the presence of bright, blue light. 

What is the circadian rhythm? 

The circadian rhythm is our body's internal clock. Relying on various environmental cues (the presence of light is the main one!), it controls our sleep/wake schedule, along with the synchronized release of various hormones, digestion, and more. 

If you wake up, go to sleep, and get hungry at the same time every day, that's your circadian rhythm at play! 

How light affects sleep

While our internal clock takes its cue from the presence of light, the mechanisms that control much of our biological processes are most responsive to blue light. 

What is blue light? 

Blue light is the higher energy wavelengths of light that comprise around 400-500 nm on the visible light spectrum. 

It's precisely this type of light that our eyes/brain pick up on to tell our body it's the start of a new day. 

What are the other types of light?

Blue light is just one bit within the entire visible spectrum of light: the spectrum of colors (red, orange, yellow, green, blue & violet) that together comprise white light. 

If blue light is the higher energy wavelength of light, red light - which sits at the opposite end of the spectrum - is the lowest energy wavelength of visible light. 

A light's color temperature can give us a clue to which color the light skews more towards - blue (awakening, energetic light) or red (soothing light that won't suppress sleep).

A " warmer " light contains less blue light and more red light, while a "cooler" light contains more blue light and less red light. 

How does blue light affect us? 

So, "cooler" light sources contain more blue light. And blue light is the main portion of light that will trigger us to stay awake.

It comes down to the hormone melatonin and a pigment in our eyes called melanopsin which is selectively sensitive to these blue light wavelengths. 

When our eyes pick up on the presence of blue light, melanopsin suppresses the production of melatonin, a hormone that is most well known to control sleepiness. 

That's why we know not to use devices too close to bedtime (or at least use blue light filters!)

But that's not all. For example, while our device screens emit blue light, so do certain light bulbs! 

Lighting tips for a good night's sleep 

-Use warmer color temperature lighting in the evening

Remember that a light's color temperature can give us a clue to which color its spectrum skews more towards - blue (energetic light that is awakening), or red (soothing light that won't suppress melatonin - the sleep hormone).

"Warmer" light contains less blue and more red light, while a "cooler" light contains more blue and less red light. 

We recommend anything 2700K-3500K. 

-Dim all lights / use lower wattage

While a lot of attention rests on light color, brightness can be equally as important. Too bright a light triggers pupillary reflex, which tells your brain that it's time to wake up! 

-Blue light filters on devices

Thankfully, these days most of our devices are equipped with blue light filters and timed color temperature controls for our screens!

-Turn off all devices at least one hour before bedtime

Remember good old paperbacks? It may be a great choice to begin rereading them!

Blue light isn't bad! 

With so much attention on limiting blue light, it's easy to get in your head that all blue light is terrible. 

Not true! 

For the same reason that we need to do away with this higher energy wavelength at night, we need it first thing in the morning to trigger the awakening of the body and mind. Bright blue light lets our body know it's time to start a new day! 

Tips to keep our circadian rhythm on track

- Go to sleep and wake up at around the same time each day. 
- Get some sun every morning! Your overhead lights during the morning and daytime should be bright and preferably more "white" in color temperature (anywhere from 4200K-6500K).
- Set a relaxing bedtime ritual and stick to it.
- Follow the above guidelines on limiting screen time, turning on screen filters, wearing blue light blocking glasses, and dimming lights. In addition, all lights should be of a warmer color temperature in the evening (around 2700K-3500K).

Best light bulbs for sleep

This article wouldn't be complete without a list of some of our favorite light bulbs for sleep! The following are some of our favorite incandescent light bulbs by Chromalux®. 

Remember, the best light color to help you sleep is anything "warm" - whether that means warm white (for LED bulbs), or any other technology of bulb that has a color temperature below 4000 or 3500K. 

Take incandescent light bulbs for example: they are naturally warmer in color temperature and therefore skew more towards the red color in their spectrum - making them the perfect candidate for nighttime usage! Unique to Chromalux® incandescents are their special glass that enhances colors and contrast, so nighttime reading becomes even easier! 

Our favorite night time bulbs, then: 

For overhead recessed lighting: Chromalux® R25 60W flood bulb

For bedside table lamps: Chromalux® B10 medium base 25W, or Chromalux® A19 60W frosted 

💡Thanks for reading!

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