I was trying to get by without my TQ on a recent overnight.
I had my UQ and wore mid-weight wool tops and bottoms to bed. Woke up in night due to chill. Tarp was set low so it wasn't convection (wind). Broke out space blanket that I have carried with me for years but never opened before.
Warmed up quickly and slept through the rest of the night. Inside of space blanket was wet in morning so I wouldn't use this as a regular sleep system nor as a layer between insulating layers.
BUT it did work as advertised and weighs 2.5 oz. Now I need to fold it up as small as it once was.