Feeling tired on a car, bus or train can be directly related to many factors. First and foremost, boredom. When not having to pay attention to the road ahead the mind can focus on other things. However, lets say you're on the train with nothing to do, nobody to talk to and zero scenery, that could get boring. And that boredom may present with a feeling of fatigue. If on the way to work your not excited at all, even a little depressed because it's monday morning and you have the whole workweek ahead of you. There's a number of mental factors that could play a role in feeling tired when you rightfully shouldn't. Depression, stress and more. The amount of sleep you are getting at night also plays a role. Six to eight hours should be enough.
Energy levels play a role when feeling tired, and energy levels vary greatly amongst individuals. Your diet and fluid intake, the types of fluid you drink (especially coffee and caffeineted drinks) all play a role. With caffeine, you may feel a boost of energy, feeling alert and ready to go...then shortly after, you feel drowsy and lethargic. This is caused by high levels of caffeine and sugar intake that are metabolized by the body quickly, leaving you feel worse than you did before.
