Warm Light vs Cool Light – Which Is Best For Reading?

What kind of light you should aim to read by depends on why you are reading in the first place.

For example, warm lighting with a Kelvin rating of between 2,000K – 3,000K creates a sense of comfort and relaxation, which is ideal if you’re at home and reading for the purpose of relaxing.

On the other hand if you absolutely need to be alert and fully engaged when reading (such as if you are studying or researching material for work purposes) cool lighting that mimics daylight and has a Kelvin ration of over 6,500K would definitely help reduce fatigue inducing melatonin levels to their lowest levels.

If you find yourself working into the wee hours and want to wind down, adjust the night light settings on your monitor to reduce the colour temperature of your screen to a warm 3,000K and invite sleep to take you away.

How does light affect the brain when reading?​

To talk about what type of light is best for reading it is important to understand the concept of light temperature, and in particular how warm light and cool light influence our ability to concentrate.

The temperature of light is measured in Kelvin (K), a unit derived from the colour an object emits as it gradually increases in temperature.

The Kelvin scale is useful to use as a reference here as it helps us quantify warm light and cool light, as well as a direct correlation with melatonin levels found naturally in our bodies, the hormone that regulates our sleep-wake cycle, or circadian rhythm.

At the lower end of the Kelvin scale are warm colours from the start of the colour spectrum. Think orange and yellow hues from a newly started wood fuelled fire.

The highest colour temperatures on the other hand reflect the appearance of an object that has been heated until it is white hot, so has cool tones from the blue-violet end of the colour spectrum.

The presence of light of any type decreases melatonin production and signals to our bodies that it’s time to wake up. During daylight hours the level of melatonin in our bloodstream is greatly reduced as the pineal gland remains inactive.

Not until we are present in a dimly lit environment once more does the pineal gland reactivate and once more release melatonin into the blood stream.

Should I use warm light or cool light in the home office?​

Light can affect our innate biological processes, and here’s how we can use that to our advantage whilst working…

  • Ideally, position your desk or work surface so that you’re exposed to natural light. This doesn’t need to be right up against a window sill but at least within a room that is flooded with bright light for as long as possible during working hours.
  • If natural light is proving difficult to come by, if for example you smartly occupy an otherwise unused space such as a corridor or storage room, it is possible to reduce fatigue and increase with artificial lighting. Blue-enriched light bulbs that mimic cool colour tones were found to result in workers reporting they were happier, more alert and feeling less sleepy during working hours.
  • If you’re unsure what colour temperatures you are being exposed to it is possible to use the White Balance Color Temp App for Android phones, or the Lumu Light Meter for iPhones to check if you are working in warm or cool light.
  • Not really a design tip but more a good habit to practice. Head outside to be exposed to uninhibited natural light during lunch breaks whenever you can.

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