what's the real effect of weighted vests?

Weighted vests are used to help students with vestibular and propioceptive processing issues to keep focus and attentive during the lessons.  Because they are being widely used among special educators it is important to keep in mind how these vests works and the time length they work.

OTR Erin Morrison wrote, A Review of Research on the use of weighted vests with children on the Autism Spectrum (2007).  The article reviews the techniques of weighted vests and evidence of effectivness in the classroom.
"the weight in the vest
provides proprioception (deep pressure),
which provides calming input to the central
nervous system by promoting the
production of neurotransmitters such as
serotonin and dopamine (2007)."

Teachers have seen vast amount of improvement in attention and a decrease in anxiety while wearing the vests.  But on the other hand, the vests are found not to have lasting effects after the vest is taken off. Therefore the effects are not long term. But the article goes with mentioning that their is no true data which can gives data to the amount of time a vest should be on, and what other factors effect the child.

Morrison, E. (2007, Spring). A Review of Research on the Use of Weighted Vests      with Children on the Autism Spectrum. Education (Chula Viata, Calif),      127(3), 323-327. Retrieved from      http://vnweb.hwwilsonweb.com.libezproxy2.syr.edu/hww/results/      getResults.jhtml?_DARGS=/hww/results/results_common.jhtml.35