Inductivist and Jason Malloy check out the General Social Survey to look at people self-reporting to have "energy all the time" over the last month. Jason writes:

wordsum IQ 

0-2: 11.6% 

3-4: 14.8% 

5-6: 10.2% 

7-8: 8.7% 

9-10: 5.0% 

Intelligence and energy have an inverse relationship! Smarter people feel a lot more drained.

Maybe smart people get worked harder. Or maybe it's just wider knowledge among smart people of how incredibly energetic some people are. Like I once spent five minutes talking to financier Michael Milken. He had a lot of energy! And he has a lot energy all the time. My favorite Milken story is about the nobody who had been trying to get a meeting with Milken for months to pitch his idea for a junk bond leveraged buy out. Finally, Milken's secretary calls to say Mr. Milken can meet with him next Sunday at 5:30 am. He says, "Great, I'll be there!" 

Then, late than night he gets a call from the great man himself. Milken apologizes for not noticing that this Sunday is going to be the first day of Standard Time, and since the clocks will Fall Back at 2 am, he'd like to change the meeting to 4:30 AM Sunday. "So, 4:30 am okay?"

Yeah, sure, Mike, no problem, I was just wondering myself what I was going to do with that extra hour!