Light therapy lamps are sold on one number: 10,000 lux. It appears on every box, and it sounds like a lot.
It is a lot compared to your living room. It is not a lot compared to going outside, and understanding that comparison tells you exactly when a lamp is worth the money and when it is an expensive substitute for opening a door.
The numbers, side by side
Lux measures how much light actually reaches a surface. The gap between indoors and outdoors is far larger than your eyes suggest, because your visual system adapts continuously and hides the difference from you.
| Environment | Approximate lux |
|---|---|
| Living room, evening | 50 |
| Well-lit office | 300–500 |
| Bright room by a window | 1,000 |
| 10,000-lux therapy lamp, at correct distance | 10,000 |
| Overcast morning, outdoors | 1,000–10,000 |
| Clear day, outdoors, in shade | 10,000–25,000 |
| Clear day, direct sun | 50,000–100,000 |
Two things fall out of that table immediately.
A therapy lamp is roughly equivalent to standing outside on a dull day. That is genuinely useful — it is ten to twenty times your office — but it is not exotic.
On a clear morning, outdoors beats the lamp by five to ten times, for free. No lamp on the market competes with an ordinary sunny day.
The distance problem
The 10,000-lux figure on the box is measured at a specific distance, usually 12 to 16 inches from your face. Light intensity falls off with the square of distance, so the drop is steep and unintuitive.
Double the distance and you get roughly a quarter of the light. A lamp sitting at the back of your desk, two or three feet away and off to one side, might be delivering 2,000 lux rather than 10,000. People buy the right lamp, position it wrongly, get no effect, and conclude light therapy does not work for them.
If you use a lamp: close, slightly above eye level, angled toward your face, and in your field of view without looking directly at it. Read the manual for the distance the rating was measured at, and then actually sit at that distance.
When outdoors wins, which is most of the time
For most people, most of the year, going outside is better on every axis: more light, better spectrum, free, and it comes bundled with movement and fresh air, which makes it a habit that survives.
Five to ten minutes outside on a clear morning does more than thirty minutes at a lamp. Even on an overcast day, ten to twenty minutes outdoors is comparable to the lamp and requires no purchase. (The full dosing guide for morning light.)
The practical version is to attach it to something you already do — walk somewhere, drink your coffee outside, take the long way to the station. A light habit that requires standing in the garden doing nothing lasts about four days.
When the lamp genuinely wins
There are real cases where a lamp is the right tool, and they are not edge cases.
You wake before sunrise. In winter at northern latitudes, a 6:30am wake time means there is no sun to get. You cannot go outside and collect light that does not exist yet. A lamp is the only way to deliver a morning signal at the right biological time.
You have seasonal affective disorder. This is the use case light boxes were designed for and where the clinical evidence is strongest. Standard protocol is 10,000 lux for around 30 minutes shortly after waking, and it is well studied. If winter reliably flattens your mood, this is worth discussing with a doctor rather than self-prescribing.
You work shifts. If you are trying to hold a schedule your local daylight actively contradicts, controlled artificial light is the only workable tool.
Your mornings genuinely do not permit going outside. Caring for a small child, a physical limitation, an unsafe neighbourhood at 6am. A lamp used consistently beats an outdoor habit you never actually perform.
What to look for if you buy one
- 10,000 lux at a stated distance. If the box does not say the distance, the number means nothing.
- A large light surface. Bigger panels are far more forgiving of head movement — you can shift position without falling out of the beam.
- UV-filtered. Standard on reputable models, and non-negotiable.
- Sensible price. The technology is not sophisticated. Reputable units sit in the $60–150 range; above that you are usually buying industrial design.
What you do not need: blue-enriched "circadian" lamps at a premium. Bright white light at sufficient intensity does the job, and the marketing gap between the two is much wider than the physiological one.
Timing beats intensity
The most common mistake is treating this as a dosage problem when it is mostly a timing problem.
Light within 30 to 60 minutes of waking produces the phase shift you want, because that is when your circadian clock is most sensitive. The same light at midday is pleasant but circadian-neutral. In the evening it works directly against you, delaying the melatonin release your morning exposure just scheduled. (How to handle evening light.)
A modest dose at the right hour beats a large dose at the wrong one. This is why five minutes outdoors at 7am outperforms an hour at a lamp at noon.
The same principle explains why light is only half the circadian picture. Morning light sets when melatonin arrives; what happens once you are actually asleep decides what those hours are worth — and the biggest variable there is whether you breathe through your nose or your mouth for eight straight hours. Titan Recovery's bamboo silk mouth tape is the simplest way to hold the nasal route while you are unconscious. (What changes across a night.)
What to expect
The payoff is delayed, which is why people abandon both approaches early.
Morning light does not primarily make you feel awake now. It schedules melatonin release roughly 14 to 16 hours later. So the first thing you should notice is not a brighter morning — it is getting sleepy earlier in the evening, usually somewhere in the first week. Falling asleep faster follows, then a wake time that stabilises on its own.
Give it two weeks before deciding. Most "light therapy did nothing for me" verdicts are delivered on day four, from a lamp positioned three feet away.
The bottom line
A 10,000-lux lamp is roughly equal to an overcast morning outdoors, and about a fifth of a clear one. For most people, most of the year, going outside is better, free, and easier to sustain — so start there.
Buy the lamp if you wake before sunrise, work shifts, have seasonal affective disorder, or genuinely cannot get outside in the morning. If you do buy one, sit close enough for the rating to mean something, and use it within an hour of waking. Timing is doing more work than intensity in every one of these scenarios.