Brief
The year was 2007, I was roughly 14. My room had a light and the light had a switch. The switch was approximately two meters from the bed. Two meters of cold floor.
I was a teenager. I had access to string, a drill, and the unsupervised confidence of a fourteen-year-old. The conditions for engineering were, frankly, optimal.
The solution
I used a piece of string, tensioned along a line from the head of the bed, up through a tactically drilled hole in the ceiling, across the room above the plaster, and down the far wall — terminating in a small loop knotted around a hanger near the light switch.
Conservatively speaking, it might have been the greatest smart home solution of its decade. No latency, no battery. The total cost of ownership was approximately seven shekels and one drill bit.
Known limitations
There were a few: The string had shortened in the winter and elongated in the summer, meaning - I had to adjust for its tension every time.
On these occasions I had to get out of bed, adjust the length, re-thread the line, retie the knot, typically at 23:30, on a school night, in the dark.