In agricultural tractors for example, as a general rule 40 to 50 percent of the value of the machine will be lost in the first quarter of the machine's life and by the halfway point of lifetime, from 70 to 75 percent of the value will be lost.
People with PTSD may feel constantly alert after the traumatic event. This is known as increased emotional arousal, and it can cause difficulty sleeping, outbursts of anger or irritability, and difficulty concentrating. They may find that they are constantly on guard and on the lookout for signs of danger.
Since vertigo is almost exclusively caused by hyperventilation, the best way to stop the feeling of having vertigo is to make sure that you're not hyperventilating anymore. Often this is easier said than done. In the middle of an anxiety attack, it's very hard to re-gain control of your breathing.