How do smart watches track sleep?

Honestly, my watch always thinks I am asleep when I am just lying in bed scrolling Instagram for hours! It basically looks at how much your wrist is moving and your pulse rate to calculate the deep and light sleep stages. It's cool but definitely not 100% accurate.

Actually, yaar, they use these tiny green lights at the back to read your blood flow and heart rate variability. Combined with your movement, the app algorithm guesses your sleep cycle. It is fun to check in the morning, but don't sweat over minor changes.

I track my sleep because managing PCOS requires good rest. My doctor told me that while these watches help us notice patterns, they can't replace a real clinical sleep study. Use it as a gentle reminder to sleep on time rather than a perfect diagnostic tool.

My smartwatch basically mocks me every morning with a 'poor sleep' notification because of my late-night coding. It tracks how dead-still you are. If you toss and turn like a paratha on a tawa like I do, it will show you got zero deep sleep.

I used to rely on my watch to check why I felt so tired, and it showed normal sleep. But later I was diagnosed with severe sleep apnea by a real doctor. If you are chronically tired, please see a specialist instead of trusting a wrist gadget.

I was researching this and found out they use photoplethysmography and accelerometers. Basically, they measure your movement and heart rate. It is fascinating tech, but we should always remember it is just an estimation based on algorithms.