Circadian-based smart sleep mask
April 2025 - Present
A smart sleep mask and mobile app using study-backed light pulses to shift and realign my circadian rhythm.
tldr
- Role
- Co-founder, hardware and software · 2-person team with Aiden Suganuma · 2025–present
- Built
- Designed the light-therapy sleep mask's housings over a few dozen prototypes; wrote its SwiftUI iOS app (3 generations) and BLE firmware
- Result
- Shipping to early customers; firmware idles the mask in low-power sleep 99% of the time; thousands of hours of personal use
- Tools
- SwiftUI, BLE, AlarmKit, embedded firmware, CAD
As I struggled with my sleep freshman year of college, I got interested in making a better alarm clock. I mentioned the idea to my friend Aiden while I was researching; he revealed that he'd been working on a smart sleep mask idea for a while, and after further discussion, we started this project.
The core idea of the Circadian sleep mask is that the human biological clock can be manipulated with artificial light. We know this to be problematic when we stay up late on computers, but, it goes both ways if you time your light properly. Many people have heard (or seen reels claiming) that natural light right after waking up can reduce sleep inertia. We go a step further and build off of a series of studies which showed that light exposure while asleep can even more drastically adjust your circadian rhythm.
We read a few dozen papers, and started making mask prototypes. I designed the housings, programmed the app, built an algorithm around the study results, and wrote the firmware for the mask while Aiden handled the custom electronics. We've produced a few dozen prototypes for better comfort and fit and are now on our third generation of the app.
The mask works by outputting light pulses at specific times based on your sleep schedule. An algorithm calculates estimates of your body's schedule using your sleep patterns and self-reported data. Then, every night, the app talks to the mask via BLE before you go to bed. It stays in deep sleep 99% of the time outside of that short window.
This was my first time using SwiftUI, and I've had a lot of fun working on the app. Currently, we're shipping masks to a few early customers that found us online, and I'm updating the app to support more alarm features including native iOS alarms with AlarmKit.
As it stands today, I've used the mask for over a year (totaling thousands of hours), and have seen long-term improvements in my average nightly sleep onset in my last semester compared to the same time last year.
