Sleep deprivation also led to an increase in the activity of the sympathetic nervous system, which controls many of the body's "involuntary" functions.
Beta blockers work by reducing activity in the sympathetic nervous system, which is one of the two major branches of the body's stress (or fight-and-flight) system.
The whole purpose of the 1986 vaccine act was to prevent the threat of sympathetic jurors from driving vaccine manufacturers out of the business, by setting up an alternate court system with scheduled damage payments.