First Post-Light Alarm Clock

Starting with a fringe health thing that sort of works–light alarm clocks. I’ll probably post more on light later. I think I actually got seasonal affective disorder unrelated to the seasons by being a shut-in. In short, blue light suppresses melatonin production and probably wakes you up in other ways so it’s good to have some in the mornings. There are alarm clocks meant to wake you up this way, but I ended up making my own because I have some decently high powered LEDs lying around.

Say hello to my little firehazard

I did this about a year ago, so I don’t remember what the LEDs actually are. They are probably 3-5W, Chinese ones from Ebay, and all hooked up in series to a cannibalized 15W wallwart power supply with a power MOSFET that I got from a broken computer power supply as a switch. The voltage drop of the combined LEDs was just about perfect for the power supply. I had those little heatsinks lying around but they probably aren’t nessesary. This is about as bright as a normal 60W incandescent bulb when at full power. I control the brightness using PWM with a raspberry pi. See the program here (, with instructions for use in the comments.

To tell the truth, I don’t use this any more. Even the tiny amount of light that gets past my blackout blinds signals daytime if I’m ready to get up, and I’ll stay in bed if not. What has worked is using orange safety glasses before bed, to aid in melatonin production, and a lightbox upon waking up.

Author: Garth Whelan


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