Breathing in and out slowly for several moments will reduce his feelings of anxiousness.
Uncontrollable anxiousness that interferes with daily life is clinical anxiety, or generalized anxiety disorder (GAD).
Having a manageable amount of anxiousness can motivate you to think harder on questions.
Most common side effects reported are behavior changes and frenzied activity or anxiousness.
In general, anxiety is a normal reaction to acute stress, and a little anxiousness can be good for you.