[wpietri]

Yes, exactly. A jarring alarm will wake me up wherever I am in my sleep cycle, and I get the same grogginess. A light alarm gets me to wake up when my body is ready to wake.

I found off-the-shelf light alarms not bright enough, so I used a bunch of Hue lights to get it brighter:

https://github.com/wpietri/sunrise

I was surprised to discover that the more valuable part was auto-dimming the lights in the evening. I'm much more likely to go to bed on time if there's been a virtual sunset over an extended period. I miss it when I travel.

[nradov]

I'm not sure what the sleep cycle has to do with it. I feel the same way regardless of when the alarm wakes me up.