> Today, electric blankets feature a dial and thermostat, none of which compensates for the fact that our body temperature, and need for heat, changes as we pass through each evening’s sleep cycle.
Then, by definition, it's NOT a "thermostat".
> Again, the solution seems obvious. The electric blanket should sense the ambient room temperature, the temperature setting of the blanket, and the activity of the person beneath the blanket, using these to generate a heuristic for when and how much heat is needed across an evening’s sleep.
Not really. It needs a... working thermostat. That in turn doesn't need "to generate a heuristic" at all. Just simple thermal sensors and
- at least, negative feedback loop (needs one transistor);
- at most, a simple routine (that can run on any MCU and leave most resources to spare) to also detect derivative, which allows to pour more power without risk of overregulation and thus compensate for heat production and leak faster.
Just in case you're new on Earth, local warm-blooded animals don't change heat output thousand times per second in hard-to-predict patterns. And if they somehow did, heat capacitance of the skin would buffer this anyway.
> the electric blanket would turn itself on at the right time, and be at just the right temperature - relative to the ambient temperature - to keep them comfortably warm. It would adjust its temperature to accommodate a falling body temperature in the hours toward dawn. It would do all of this invisibly and automatically.
Which is... EXACTLY what is called "thermostat": an automatic device for regulation of temperature. Usually, for keeping the temperature inside... uhhh... STATIC. With given precision.
When this word doesn't appear on boxes with unreasonably priced gadgets aimed at the Muckbug crowd, at least.
> An electric blanket would be hard pressed to do all of this computationally expensive work on its own.
I don't see why regulating temperature even separately for different locations rather than average would need anything beyond a bunch of operating amplifiers and capacitor integrators.
But if you want to do it a really fancy way, sticking 8-bit MCU into it would do. It won't be hard pressed at all. Not unless your head is so deep down C# or Java rabbit hole that you need several megabytes of RAM to emulate capabilities of circuitry "programmable" with one variable resistor, that was primitive 50 years ago when it was used in incubators.