Arbor Networks recently studied Internet traffic patterns and found that U.S. Internet traffic usually reaches its highest point of the day at about 11 p.m. Eastern time and stays pretty high until about 3 a.m. What’s keeping Internet users up at night? Arbor found the answer.

Those of us with Internet-related day jobs may be surprised to see that Internet traffic doesn’t actually peak during business hours. It gets close. Traffic grows steadily after 6 a.m., right up until the afternoon, and hits a high point around 4 p.m. Then everyone breaks for dinner and perhaps the commute home. Traffic doesn’t really ease up that much, though, and after 8 or 9 p.m. it shoots back up, hitting the aforementioned peak at 11 p.m. (all times Eastern).

Interestingly, by contrast, European Internet traffic peaks around 7 p.m. and drops off until the morning business hours.two main factors behind the 11 p.m. peak.

According to Arbor’s studies, there appear to be

One is gaming. Arbor found that World of Warcraft’s Battlenet traffic jumps 30% exactly at 8 p.m., which is apparently a popular time for WoW guilds to kick off quests. Traffic from Battlenet peaks around 11 p.m. and then drops off rapidly.

Another type of traffic that shows up is from Steam, which powers many multiplayer first-person-shooter games. This curve is a little different, though – jumping up at 2 p.m., peaking around 8 p.m., and staying quite high through midnight.

The second main factor is video streaming. This is also primarily an afternoon and evening activity, but it peaks at midnight. YouTube serves up a lot of that video, as do adult content sites at the later hours.

So, in a sense you could say that what’s keeping Internet users up at night is sex and violence.