Asked by: Solang Uk, Switzerland
When you sleep, your muscles lose tone and fluid tends to pool along your back. Stretching helps to massage fluid gently back into the normal position. Also, your muscles protect themselves from over-extension by inhibiting the nerve impulses as they approach their limit.
Over time, this safety mechanism becomes increasingly restrictive. Stretching briefly takes your muscles outside their normal range. This recalibrates the feedback mechanisms that determine their normal amount of motion. Subscribe to for fascinating new Q As every month and follow on Twitter for your daily dose of fun facts.
Edit: the removed comment from linked to a magazine story; the journal article behind the story is. Although GABA is a chemical, it s only sent from one cell to the next along a chain of nerve cells that make up a nerve. This isn t the same as releasing a chemical into the body to float around; it s essentially just a slight change to the same electrochemical processes that makes nerves work in the first place.
We don t say that there s a drug released generally into the body to make muscles move, so we can t look at changes to the same process and now say there s one released to make them not move.  Brooks P. L. , and Peever J. H. Identification of the transmitter and receptor mechanisms responsible for REM sleep paralysis.
J Neurosci. 2012 Jul 18;32(29):9785-95. doi: 10. 1523/JNEUROSCI. 0482-12. 2012.