Dr. Matt Walker

So proprioception is fascinating.

As you're walking with a colleague and you're crossing over a street,

Have you ever had that feeling where you're sort of, you step off the curb and you're chatting and all of a sudden you have one of those really ugly wobbles where you can, ooh.

And it's because you had calculated non-consciously and computationally, you understood where your foot was in space.

You understood the velocity force with which it was descending down onto the road below you.

You had miscalculated the distance.

and your brain had expected your foot to hit that road at a certain time, and it did not.

It sends an error signal back up your spinal cord, and that's where you get that .

And you almost then have to stop the conversation that you are having because it takes over and you switch from non-conscious proprioceptive and you switch over.

So the issue is that when you are lying there awake in bed, you sense the mattress underneath you.

You sense the support.

You're getting all of that feedback signal that I was telling you was absent when you...

inappropriately calculated the distance down onto the road.

All of that is in place and your brain is saying, everything's fine.

But as we're drifting off into sleep, we start to lose that proprioceptive feedback.

Now, normally that loss of proprioceptive feedback and sensation of what's going on and where my body is,

is before the loss of consciousness.

And so you lose consciousness and that's then thereafter when the loss of proprioception happens and you don't have this sort of mental freak out of proprioceptive break glass in case of emergency.

But sometimes the speed with which those things happen changes and you start to lose the proprioceptive sensation before you fully lose consciousness.

And at that point, your body says, oh my goodness, mattress has just disappeared and I'm falling.