How to handle long afternoon & behavior issues?!

    I am a 2nd year kinder teacher after having taught sped
    for several years. I really struggle with behavior in
    the afternoon. We aren't allowed another recess (besides
    lunch-recess from 11:00-11:45. By the afternoon
    (especially 2:00-3:30) the kids are simply nuts. I am
    contemplating a 'break' or 'relaxation time' in the
    afternoon for 10 minutes or so. They know we have
    Centers (play time) at 3:00 but many simply cannot hold
    it together the last hour or so. Any ideas? We don't do
    naps in Kinder at my school. Thanks!!!!