Tonic Immobility (also known as 'apparent death') is the act of 'playing dead' and is a defence mechanism used by various animals as a response to a threat. Perhaps the animal most associated with tonic immobility is the possum, which is where the phrase "playing possum" comes from. It is also very common for marine animals and reptiles to play dead.

However, this study asks the question, 'Is there tonic immobility in humans?'. The way they conducted the experiment was by getting participants who suffer from traumatic stress and then reading out their experiences to them: "Reports of script-induced immobility were associated with restricted area of body sway and were correlated with accelerated heart rate and diminished heart rate variability, implying that tonic immobility is preserved in humans as an involuntary defensive strategy."

An example I've been thinking about for a while is when we cover ourselves in a blanket at a young age (or if you're like me you still do it). We do so in order to divide ourselves from the supposed threat that stands outside the cover, though realistically the blanket will fail to defend us in any way. This means that we put our trust and our hope into the blanket, rather than being consciously aware that it is not a suitable defensive mechanism.
Does this stem from the basis of tonic immobility?

Thoughts?