SAD lamp for the desk: bright-light session or task light?

Two lighting jobs at the desk

When people talk about a SAD lamp at the desk, they often mean two different things. One is the short, bright light therapy session in the morning, above all in the dark season. The other is the light that illuminates the work surface evenly and without glare over many hours. The two jobs have different requirements, and one lamp rarely does both at once.

The bright light therapy session depends on the illuminance at the eye. It is given in lux and falls sharply as the distance from the light surface grows. A lux figure without a distance therefore says little. The task light, by contrast, should make the keyboard, papers and notes clearly visible without reflecting on the monitor. Here the adjustment range, light distribution and freedom from glare matter more than the highest lux figure in the listing.

We did not have any of these lamps in hand and we have not measured anything. The page is based on manufacturer documents and listing information, which we have evaluated on the respective product pages. There is no documented hands-on testing for any of the models named. If you want to read up on the basics of use, our guide Using a SAD lamp correctly will help.

A clarification of terms first: on this page we use the term light therapy session for the short, bright use of a SAD lamp. By task light we mean the light that lies on the desk surface throughout the working day. We draw this separation because listings like to mix the two and so give the impression that a single lamp solves both jobs.

Distance decides the lux figure

For SAD lamps, the measuring distance is the most important additional piece of information. The documents for the models named here show how much it varies. For the Beurer TL 30 SAD lamp, Beurer gives, according to the manufacturer, 10,000 lux at a distance of about ten centimetres and a light surface of roughly 12 by 20 centimetres. For the Beurer TL 41 Touch SAD lamp and the Beurer TL 45 Perfect Day SAD lamp, the listing in each case gives about 10,000 lux at 20 centimetres.

For the Trayvespace clamp SAD lamp 18 W, the seller's instructions are more precise than the listing: there the 10,000 lux apply at a distance of 25 to 30 centimetres and only at the highest of five brightness levels, and the lowest level is given as 2,000 lux. For the Trayvespace SAD lamp with gooseneck, 12 W, the listing gives 10,000 lux but no measuring distance. This figure cannot be assessed without asking the seller.

For the desk this means in practice: plan the distance in before you buy. A device that reaches its full illuminance at ten centimetres has to be very close to your head. That can get tight between keyboard and monitor. A device with 25 to 30 centimetres gives you more room, but still needs a spot at the side of your field of view. Where light falls flat onto the screen, it reflects there. Place the light surface to the side of the monitor, therefore.

There is also the question of duration. The duration of use is set by the instructions of the respective device, not by a general rule of thumb. For devices with no documented measuring distance, such as the Trayvespace SAD lamp with gooseneck, 12 W, you should ask the seller for the details before first use.

Design and space: clamp, base or gooseneck

Desk space is scarce. The design therefore often matters more than a few lux. Three variants appear in the documents.

• Clamp: The Trayvespace clamp SAD lamp 18 W clamps to the desktop. According to the seller's instructions, the clamp fits desktops up to 5.8 centimetres thick. This frees up surface space but requires a suitable desk edge.
• Base with holder: According to the listing, the Beurer TL 30 SAD lamp has a continuously adjustable clip base for portrait and landscape orientation. The Beurer TL 41 Touch SAD lamp is described in the listing as a compact device with a base for the desk.
• Gooseneck: According to the listing, the Trayvespace SAD lamp with gooseneck, 12 W uses an adjustable gooseneck. It allows you to bring the light surface closer to your head and field of view. Stability is not proven, as there is no documented hands-on testing.

Before buying, check the depth of your desk and the thickness of the desktop. If the monitor stands far forward, little room is left at the side. With clamp solutions, it is also worth looking at the cable and socket so that the lead does not run across the work surface.

Controls, colour temperature and medical device status

The models differ markedly in colour temperature. According to the listing, the Beurer TL 45 Perfect Day SAD lamp offers three colour temperatures: 6,500 kelvin for the therapy phase, 5,000 kelvin for concentration and 3,000 kelvin for relaxation. The official instructions confirm the three adjustable colour temperatures. According to the seller's instructions, the Trayvespace clamp SAD lamp 18 W covers five colour temperatures from 3,000 to 6,000 kelvin, and the listing for the Trayvespace SAD lamp with gooseneck, 12 W gives three light colours and nine brightness levels.

On controls, the listing for the Trayvespace SAD lamp with gooseneck, 12 W gives a timer with 15, 30 and 45 minutes and a memory function that stores the most recently chosen setting. According to the listing, the Beurer TL 41 Touch SAD lamp is operated with a touch button, and the Beurer TL 30 SAD lamp with a single-button control. Whether settings change through accidental touching cannot be read from the documents.

Medical device status is a point of its own. The listings for the Beurer TL 30 SAD lamp, the Beurer TL 41 Touch SAD lamp and the Beurer TL 45 Perfect Day SAD lamp list the devices as a medical device for use in conditions caused by a lack of light. For the Trayvespace clamp SAD lamp 18 W, classification as a medical device is documented neither in the instructions nor on the product page, and for the Trayvespace SAD lamp with gooseneck, 12 W the listing also gives no such classification. This is relevant for desk use if you want to use the lamp specifically for light therapy.

Important: light therapy does not replace medical treatment. If you have eye conditions, take medication that makes you sensitive to light or have mental health conditions, you should clear its use with a professional beforehand. The instructions for the Trayvespace clamp SAD lamp 18 W also advise seeking medical advice during pregnancy. You can find more in the guide SAD lamp: side effects.

Desk models compared

The table sets the six models named side by side. It contains only information that appears on the respective product page. Manufacturer or seller documents are marked as such, and everything else comes from the Amazon listing and is unchecked.

No ranking follows from the table. It shows which information is documented and where gaps remain. If a documented measuring distance matters to you, the Beurer TL 30 SAD lamp and the Trayvespace clamp SAD lamp 18 W are the most transparent. If you are looking for a lamp classified as a medical device, you need a model with a corresponding statement. A direct comparison of the two Beurer devices is in Beurer TL 41 versus TL 45.

Suits you if: choosing by space and task

Instead of a single pick, here are conditions by which you can recognise your model.

• Little desk surface, fixed desk edge: The Trayvespace clamp SAD lamp 18 W suits you if the desktop is thinner than 5.8 centimetres and you can guide the light surface along the side edge. It is an alternative to a free-standing device when floor space is lacking.
• Documented classification as a medical device: The Beurer TL 30 SAD lamp suits you if you are looking for a lamp whose manufacturer gives 10,000 lux at about ten centimetres and which is listed as a medical device according to the listing. For this you have to get close to the light surface.
• A little more distance from the lamp: According to the listing, the Beurer TL 41 Touch SAD lamp and the Beurer TL 45 Perfect Day SAD lamp give 20 centimetres as the measuring distance. The TL 45 also offers three colour temperatures.
• Flexible position at head height: The Trayvespace SAD lamp with gooseneck, 12 W suits you if you value the gooseneck and are prepared to ask the seller for the missing measuring distance.

A different yardstick applies to task light. If you work at the monitor for long periods and do not yet have additional task light, none of the light therapy lamps solves the problem on its own. According to the manufacturer, the LitONES ComforGlow F630 is a task light with 1,750 lux, 18 watts, a colour rendering index greater than 95 and an adjustable arm with five joints. The manufacturer gives no measuring distance for it. The listing differs from the manufacturer's information in several places (15 instead of 18 watts, three instead of five colour modes), so for us the manufacturer's values apply. It is not a light therapy lamp and carries no classification as a medical device.

Whether a monitor light bar, clamp lamp or floor lamp makes more sense as task light is answered by the guide Monitor light bars: when they make sense. What brightness should arrive at the workplace is described in Lumens for a desk lamp.

Setting up and planning at the workstation

Plan the lamp as part of your whole workstation. The light surface belongs to the side of the monitor in your field of view, not behind it and not directly in front of it. You do not look into the lamp, you read, type or work on papers. Because the advertised lux values apply at short distance, the space may be tighter than you are used to.

Do not count the light therapy session towards your task light. They are two roles. A desk lit evenly with no reflections on the display eases the strain when working, even if the light therapy session runs in the morning. With the lighting calculator you can go through your room and your lighting tasks before you decide on a model.

If you are planning light for studying and focused work, you will find further points in the guide Light for studying. An overview of other designs and uses is offered by the page SAD lamps at a glance.

One more note on sources: there is no manufacturer document for the Beurer TL 41 Touch SAD lamp, and its information comes from the listing. We prefer a few models with clearly marked sources to a long list with gaps. Where a value is missing for us, it is not shown, and where the listing and the manufacturer contradict each other, we give both.