How many lux for light therapy? Choosing the right output for your lamp

Lux output is one of the most important criteria when choosing an effective light therapy lamp. It's also one of the most misunderstood. Between marketing claims and real-world usage, it's easy to get lost.

Here's a straightforward guide to understanding what lux actually means — and which intensity to choose based on your needs.

Lux: what does it actually mean?

Lux measures the amount of light received by the eye. The higher the number, the more intense the light.

In light therapy, this intensity is critical — it's what triggers the biological mechanisms you're looking for:

  • regulation of melatonin (the sleep hormone);
  • stimulation of serotonin (mood and energy);
  • resynchronisation of the internal clock.

In other words: without sufficient intensity, effectiveness drops sharply.

The benchmark: 10,000 lux

The majority of studies and protocols recommend exposure to 10,000 lux. It's the reference standard today for:

  • Seasonal affective disorder (SAD)
  • Winter fatigue
  • Sleep disorders related to lack of light

At 10,000 lux, a session typically lasts 20 to 30 minutes.

It's the best balance between effectiveness and comfort.

Lower intensities: are they effective?

Yes… but with trade-offs.

The lower the intensity, the longer the session needs to be:

Intensity Average duration Effectiveness
10,000 lux 20 – 30 min Optimal
5,000 lux 45 – 60 min Good
2,500 lux 1 – 2 h Limited

These lower intensities can be suitable:

  • For maintenance use
  • If you have light sensitivity
  • As a complement to natural daylight exposure

But they're less practical for everyday use.

Distance matters — a lot

A critical point: the stated output always depends on distance.

A lamp rated at 10,000 lux might:

  • deliver 10,000 lux at 15 cm;
  • but only 2,500 lux at 40 cm.

The further away you are, the faster the intensity drops.

That's why you should always check:

  • the distance recommended by the manufacturer;
  • the size of the light surface;
  • the diffusion angle.

Lamps vs glasses: different lux scales

Light therapy glasses typically show much lower outputs (1,000 to 2,000 lux).

But you can't compare them directly:

  • the light is aimed directly at the retina;
  • the distance is virtually zero;
  • exposure is continuous throughout your activity.

Result: despite the lower figure, the effectiveness is still real.

Which intensity for your goal?

Goal Recommended intensity
Seasonal affective disorder 10,000 lux
Winter fatigue 10,000 lux
Sleep rhythm disruption 5,000 – 10,000 lux
Light use / maintenance 2,500 – 5,000 lux
Glasses 1,000 – 2,000 lux

My recommendation after testing

If you're just starting out, I'd strongly recommend:

  • a medically certified 10,000 lux lamp;
  • usable at 30 – 50 cm minimum;
  • with an adjustable intensity setting.

It's the most versatile format — effective and built to last.

Key takeaways

  • lux measures the light intensity received by the eye;
  • 10,000 lux = the therapeutic standard;
  • less lux = longer sessions;
  • distance changes everything;
  • lamps and glasses can't be compared on lux alone.

Choosing the right intensity means ensuring your light therapy actually works… from the very first weeks.

Further reading