Answer:
Less need for sleep.
explanation:
More anxiety is, of course, not a benefit, as anxiety can really wear down the body, so we know this is not our answer.
Better concentration would probably be a benefit from more sleep and better rest, not physical activity. this also, is not our answer.
More weight gain would not be a result of physical activity, loss of weight would be. this also is not our answer.
Less need for sleep would be our answer, physical activity results in a person being in better shape, and therfore having more energy. And not feeling sleepy all the time. this does not mean you don't need sleep (9 hours is recommended) just that you won't always need to rest.