Yes, that sort of fits for what the trials with heavy blankets did to me, not as a mental fear, but physically, unfree, pinning me down... Someone told me if it's too much then they just throw it off, but this feeling lingers on in me for quite some time, causing great discomfort, which makes me have to get up or even (cold) shower to be able to sleep again.
That may be different due to fibro: It reminds me of me needing cuddling at night before fibro, but hardly tolerating it since then. Some of the people who like weighted blankets say it's got to do with the cuddling feeling. That's the reason why I thought it might be something for me.
Another factor may be like Mirador also says that I often get warmer & colder all night, have to balance that out quickly with more or less clothes, duvets, but small things/changes (apart from always 4 pairs of socks).
May sound silly, but I sometimes wonder if not feeling cuddled ('loved') enough (all my life actually) was an emotional cause of fibro - altho that seems to contradict not tolerating it for long now...
Some people intensify it by also using compression gloves and socks. Tried tighter socks myself to prevent more varicosis, but didn't like that either, prefer just putting my legs up as often as possible.