feeling very sleepy for two hours after running

I found that I always feel very sleepy for two hours after running
(usually 30-40 minutes of aerobic running) but then feel very
energetic. I used to run around 4:00-5:00 in the afternoon and I will
feel very tired for two hours then feel very energetic and many times I
will have problem to fall into sleep. So I tried to run in the morning,
and I still feel very tired for two hours after running, my morning
working hours become very unproductive, but I feel much better
afternoon.

What I can do? Should I eat some engery bar right after running?

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