If you have low blood volume and your BP is on the low side, they you should be safe to eat lots of salt. Some patients crave salt. Also try to drink lots of fluid. Some patients feel better from this, but usually only noticed in mild stages. Increase the plasma volume particularly.
Astronauts have to helped out of the capsule - get orthostatic symptoms.
A. Alcohol is very rarely enjoyed by ME sufferers. Alcohol dilutes the blood vessels and decreases the blood flow to the brain. It turns off adrenal hormone more than before. Next day - brain is shrunk and have lost circulating blood volume. To avoid a hangover drink three or four glasses of water before bed.