This is my first winter in Boston after coming back from Senegal. The sun sets at around 4:15 now, and it’s suddenly become extremely salient how hard it is for me to focus after dark.

I’d vaguely noticed this in the past, and dealt with it by shifting my sleep schedule earlier (or just being unproductive). But I’m waking up around 6:30 now and I already struggle to stay up for evening events. So finally, inspired by some blog posts, I decided to give up on chasing natural sunlight and make my own instead.

I bought an extremely bright “corn cob” style bulb. It emits as much light as about 40 incandescents, and produces enough waste heat that it needs an internal cooling fan to dissipate it. I put it next to my desk, in my peripheral vision (it’s somewhat uncomfortable to look at directly). According to my questionably-accurate iPhone light meter, its reflection off the curtains in front of me is brighter than the actual sunlight coming in from the outdoors (at 600 lux), and overall light levels in my interior went from 50 to 400 lux (“sunrise or sunset on a clear day”). (source).

The effect was huge: I became dramatically more productive between 3:30pm and whenever I turned off the light. Instead of having a strong urge to stop working whenever it got dark out, I was able to keep working my normal summer schedule, stopping just before dinner. I estimate the lamp bought me between half an hour and two hours a day, depending on how overcast it was.

To try to capture the difference, I used a manual camera app to take before and after photos of my desk with the same exposure and white balance. The phone camera doesn’t really capture the full effect since the dynamic range is so small, but hopefully it conveys a little bit of the amazingness:

Drag the white triangle to compare.

Everyone who’s visited my house after I installed the bulb has remarked on how cheery our living room now is, some of them before noticing the light. My partner and several friends are buying their own.

For reference, here’s the stuff I bought (note that the bulb is on sale today):

The cheapest-per-lumen “corn bulb” I could find on Amazon, $100 for 30,000 lumens. Note that this one has a built-in cooling fan that runs decently loud (45db at 1m according to my questionably-accurate iPhone sound level meter). If that bothers you (it kinda bothers me), you can buy two of the 120w ones, which don’t mention fans in the description.

These E26 to E39 adapters that will allow the bulb to be put in normal sockets.

I didn’t want to mess around with my existing fixtures, so I bought a basic fixture rated for 250 watts.

Notes:

The clamp on the fixture does nothing with this bulb because it’s too heavy—just take it off.

If you don’t want to turn the bulb off by unplugging it, consider an outlet switch like this one (I haven’t tried it personally).

Originally I stabilized the fixture by wedging it inside a piece of the lamp’s packing foam (see picture), but today I realized that I could rest the metal guard inside an empty 2lb yogurt container instead, which is better because it leaves room for the power cord to run.

if you want to put your bulb in an existing fixture/socket instead, make sure to check (a) that it will fit (it’s very large) and (b) that the socket is rated for 250w (many aren’t).

Why doesn’t everybody do this?!

All the blog posts were written by/about people who were described as having “crippling” seasonal depression. I’ve never been depressed, which is why it took me so long to give it a try (or even notice the correlation between light and productivity).

In retrospect, that was silly. “Seasonal affect disorder” makes it sound like it’s a discrete thing that you have or don’t, but probably everyone has noticed they’re more lethargic on cloudy days. A better model might be that seasonal depression is just the tail end of a curve in how people respond to light:

Typical indoor light levels run from 100-500 lux, which at the high end is about as bright as sunrise outdoors, and about 100x dimmer than daylight. Other than “we’ve been doing it for a while,” there seems to be no reason to expect that being in a 100x dimmer environment all day wouldn’t be awful. Indoor darkness seems to be one of those things that we don’t question only because it’s been that way forever.

Until recently, though, questioning it would have been somewhat academic, because it was too expensive to buy (and power) enough bulbs to do anything about it. My bulb is an LED bulb, for which cost per lumen has been falling about 20% per year for the last 50 years (source). LEDs only passed fluorescents in efficiency recently, but they’re still dropping fast. 10 years ago a bulb as bright as mine might have cost $1,000 instead of $100.

But as of recently, it’s totally practical to fill your entire house with light that’s as bright as full daylight. Ambient daylight in the shade is about 10k lux, or 10k lumens per square meter. For a 70 m2 apartment, that would be 700k lumens. The bulb I bought is $100 for 35k lumens, so $2k would buy sunlight for the entire apartment. (In another 10 years, if LEDs don’t hit physical limits, it’ll be $200!)

To close, some ultra-bright-lamp FAQs:

How is this different from “light therapy lamps”? Light therapy lamps are weak. They only give you a reasonable amount of light if you point them directly at your face from around a foot away. A high-power corn bulb makes your entire room much brighter, thus providing a much better simulation of daylight. See “You need more lumens."

Isn’t this expensive to run? It draws about 2 kWh per day (assuming 8h of usage), which costs about $0.30 at typical rates. This is comparable to one day of a modern fridge or one load of laundry. Power is cheap, folks!

Isn’t using this much power bad for the planet? Coal has a carbon intensity of about 1 kg CO 2 e / kWh (source), so one coal-powered lamp-day produces 2 kg, approximately one-third to one-half of a cheeseburger (source).

Isn’t 5000K very “cold” light? “Cold” lights (above 2700k, the typical incandescent color temperature) have a bad reputation, but 5000K is actually less cold than the sun (which is about 5500-6500K), which clearly does not have a bad reputation. My totally non-validated theory is that people don’t like cold light because most cold lights (historically, mostly fluorescents) have much worse color rendering than incandescents: that is, they emit light only in discrete parts of the visible spectrum, which changes the relative appearance of colors and makes everything look weird. For instance, compare the two example spectra of a fluorescent vs. an incandescent:

Doesn’t it make it hard to sleep? Yup, bulbs this bright suppress my sleepiness dramatically (that’s partly the point!). I shut it off every day when I’m done working, usually at 6pm, about 3 hours before bedtime.

What are the downsides? The lamp flickers when other current-hungry appliances turn on, has a loud fan, looks ugly, is hard to set up a nice fixture for, doesn’t have an on/off switch (I just unplug it), and doesn’t make it easy to provide even illumination throughout a space. I’m working on building a DIY ultra-bright lighting setup that I expect to be way more effective on all these dimensions—stay tuned.