1) any part of you out from under the blankets (face, perhaps) feels the coolness.
2) I can't sleep with few or no blankets anyway. I mean I could probably adjust to it over time, or if I'd hiked 20 miles that day I bet I could, but I certainly can't right now under ordinary circumstances.
I don't start to think a room's too cold for comfortable sleeping until it's under like 60F. My sleep gets worse if it's over about 68.
2) I can't sleep with few or no blankets anyway. I mean I could probably adjust to it over time, or if I'd hiked 20 miles that day I bet I could, but I certainly can't right now under ordinary circumstances.
I don't start to think a room's too cold for comfortable sleeping until it's under like 60F. My sleep gets worse if it's over about 68.