[snickell]

They run cooled/heated water through them, the idea being that temperature can trigger / lengthen certain phases of sleep. Think getting into a warm bed that gets colder as you go into deep sleep, and then when the night is done warms up again for wakeup. In my case, it seems to work really well, but I have the same resistance/frustration with the ongoing subscription.

[elzbardico]

It shouldn't be too complicated for a motivated hobbyist/hacker to retrofit it to run it with some custom DIY hardware eschewing the subscription need completely.

After all, it is just a couple of pumps, a heat pump and/or a resistance and some sensors.