From Psychology Today:
According to Mr. Kanazawa, staying up late is “evolutionarily novel” and thus night owls are likely to be more intelligent than their early rising counterparts. Kanazawa states that there is no evidence in the history books of traditional nocturnal activity (before artificial light), so we can assume that our ancestors were mostly diurnal (day people). Thus, being nocturnal is, as stated above “evolutionarily novel,” and, as we know, further along the evolution chain should mean smarter (maybe. Or stupider. Hmm).
Hah! So next time someone gets on my case about staying up til six in the morning, I’ll just shut them down with a “CAN’T. HEAR. YOU. TOO. BUSY. BEING. A. GENIUS. KTHXBAI!”