Before building anything I wanted a list of health devices that pass three tests:
- It would help me. I am a student who sits at a screen all day.
- You cannot easily buy it. It is missing, overpriced, or locked to one brand.
- It is measurable. It moves a number that research says matters.
I went through about 35 ideas across sleep, light, air, water, posture, eyes, hearing, teeth, food and fitness testing. Thirty were cut.
Why most ideas died
Your phone already does it free. Noise exposure tracking is built into iPhones and recent Android phones. Sleep regularity scores come with any watch. Screen dimming is in every operating system, and a trial of 167 people found it made no difference to sleep anyway.
It is a A$50 commodity. A CO2 monitor used to cost A$300. IKEA now sells one for A$49.99. Air purifiers, sunrise alarms and light therapy lamps are the same story.
The evidence fell over when I read it.
- Posture trackers: a 2025 review found no good evidence they reduce pain.
- The 20-20-20 rule for eye strain: a lab study found little or no effect.
- Mouth tape: a 2025 review of ten studies does not support it.
- Sound that boosts deep sleep: the effect shrank to nothing as studies got better.
- Grip strength training for a longer life: grip predicts lifespan, but a genetic study suggests it is a sign of health, not a cause.
It needs a lab. Testing water for PFAS or lead, measuring blood glucose, measuring blood pressure without a cuff.
The five that survived
| Build | What it does | Rough cost |
|---|---|---|
| A light meter for your eyes | Scores your day, evening and night light | A$60 to 90 |
| A seven minute fitness test | VO2max and recovery from a chest strap | A$0 to 30 |
| A grip trainer for blood pressure | Coaches the routine from the trials | A$40 to 70 |
| A chair that knows when you cheat | Times sitting, verifies walking breaks | A$40 to 80 |
| A bedroom logger | Links room conditions to your sleep | A$120 to 160 |
Only the first two are strong on all three tests. The other three each have a real weakness, which is written on their pages.
Two more builds are already under way: Breathband, a band that paces slow breathing, and a night schedule for my bed cooler.
What happens next
Each build has a follow button. I will build in the order people follow them, starting with the bed cooler because I already own the expensive half of it.
If you think I cut something that deserved to live, or kept something that does not, tell me. Being wrong in public is the point.