When choosing daylight light bulbs it’s worth noting that light bulbs with a ‘daylight’ colour temperature are not the same as ‘full-spectrum daylight’ light bulbs which are used to treat Seasonal Affective Disorder (SAD). The latter produce light across the whole colour spectrum (rather than just mimicking the colour of daylight).

Daylight Light Bulbs

Daylight bulbs are so named because they replicate the natural light seen on an overcast day. If daylight bulbs are installed indoors, they can look very blue and, as a result, they don’t create a very cosy atmosphere. This colour is best avoided in bedrooms and living rooms and can be used instead for areas where accurate colour reproduction is required, such as retail, display and workplaces.

Daylight bulbs also excellent for outdoor lighting or for areas where natural daylight enters through a window but the room is still too dim and needs brightening.

There are four main types; LED Daylight Bulbs, Daylight Tubes, Incandescent Daylight Bulbs and Energy Saving Daylight Bulbs.

Seasonal Affective Disorder (SAD) Light Bulbs

Seasonal Affective Disorder (SAD) affects a large number of people in the UK, particularly during the winter months. The prolonged nights and shortened days of winter limit the amount of sunlight many people receive during the darkest winter months.

A notable treatment for these symptoms is the use of full-spectrum daylight tubes that can adequately mimic the quality and spectrum of light provided by natural daylight. Check out our range of full-spectrum and daylight tube lights here.

LED/Fluorescent Daylight Tubes

Different types of environment generally require different types of light source and colour. Many employers find it useful to use daylight tubes to illuminate their workspaces, owing to their generous light output, wider spectrum and superior CRi (more on these last two later).

Most people in north western Europe spend much of their working lives indoors, either in offices, warehouses or other enclosed spaces. This can ultimately deprive them of the natural daylight they would normally receive from direct sunlight.

While this can make for a pretty miserable working environment, in extreme circumstances it can also cause certain psychological disorders such as SAD…

Colour Rendering Index

The Colour Rendering Index is an industry-standard reference to a light bulb’s ability to render the colour of an object it is illuminating correctly. Codes range from 0 to 100, with the higher numbers denoting more vivid and lively results. A lower CRi rating produces more ghostly (faded, dead) effects. If you want certain items to look good under lights – either for photographic or display purposes – then a higher CRi is required.

Bulbs with a high CRi rating generally cost more to buy and more to operate as they yield fewer lumens per watt consumed. Lower CRi light bulbs put out lower quality light but are very cheap to operate as they have a higher lumen to watt ratio.

You can read more via our guide on the colour temperature scale.

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Hi, I have a recipe where I need to soak and germinate whole grains under the sun, from sunrise to sunset. Is there a lightbulb that mimics the sun, for use when it is cloudy?
Thank you

Ray Winfield

Are daylight bulbs beneficial for house plants? Winter can be a nightmare for tropical plants that need natural light and it also helps us too.

Mat @ Lightbulbs Direct

No, not as affective as a lightbulb specially designed for growing plants. The daylight colour is a mixture of red, green and blue light and doesn’t colour the full spectrum of light that sunlight gives.


I am trying to replace a couple of Osram Dulux F 36 W 28-835 CFLs with LEDs. Is this possible?

Mat @ Lightbulbs Direct

That light bulb is quite unique, and we haven’t yet seen any LED replacements that are available.

H Hicks

I cannot find your SAD lightbulbs even though I’m invited to “check them out here”. Do you have any and what price are they? Thanks.

Mat @ Lightbulbs Direct

We no longer stock specific ‘SAD’ light bulbs, but you may find a daylight light bulb does the trick