If you have a tough time pulling your head off the pillow in the morning or settling into bed at night, it could be a sign you’re brainy.

Satoshi Kanazawa, a psychologist at The London School of Economics and Political Science has done extensive research on the connection between sleep patterns and intelligence.

His findings indicate that people with higher IQs tend to stay up later, and subsequently wake up later in the day.

Sleep & Smarts Stats:

Bedtimes and wake-up times for Americans in their 20s by IQ.

Very Dull (IQ < 75)

Weekday: 11:41 P.M.-7:20 A.M.

Weekend: 12:35 A.M.-10:09 A.M.

Normal (90 < IQ < 110)

Weekday: 12:10 A.M.-7:32 A.M.

Weekend: 1:13 A.M.-10:14 A.M.

Very Bright (IQ > 125)

Weekday: 12:29 A.M.-7:52 A.M.

Weekend: 1:44 A.M.-11:07 A.M.

Kanazawa theorizes that humans used to rise and fall with the sun, 10,000 years ago. Now that electricity enables a more nocturnal lifestyle, below-average and average brains still want a sleep pattern that resembles our ancestors’. Whereas above average brains will ignore that impulse and find stimulation during the later hours.