Symptoms common to both include memory problems and impaired concentration, social withdrawal, anhedonia (loss of pleasure in life and activities), sleeping too much or too little, agitation and despondency.

But even they are not protected from the insomnia, impaired concentration, slower intellectual responses and irritability encountered by most intercontinental travellers.

He also used the same over-the-counter medication to help treat the associated attention deficit, hyperactivity, impaired concentration and distractibility.