By Jason Palmer
Science and technology reporter, BBC News
Social networking sites overtook adult sites in popularity in September 2008
Sunday morning is proving a popular time for watching pornographic movies, a video on demand site has found.
Analysis of viewing figures shows peak demand for FilmOn's "naughty movies" was around 1116 GMT on Sunday.
By contrast, internet analysts Hitwise found that usage of video sites peaked on Sundays but more traditional adult sites experienced a dip.
Sundays, it said, was the top day for visits to internet shopping and social networking sites.
Explaining the film viewing data, Alki David, founder of FilmOn, said: "The data applies to both men and women and it certainly poses the question about what has happened to the traditional 'day of rest' in Great Britain."
The figures for January were uncharacteristically high, given the slump that typically follows the holiday season. But Mr David was unsure why adult content was favoured.
"I have no idea," he told BBC News. "It may have to do with the Winter and the oncoming depression. Cheap entertainment seems to be faring quite well right now, and adult content is the most extreme distraction of all."
Different genres of downloaded videos peaked on different days; "family viewing" films experienced a peak on Wednesdays, while sport-related titles showed a Saturday spike in sales.
This chimes with Hitwise's figures across all sport-related sites, which have a pronounced peak on Saturdays around 50% higher than any other day of the week. This, according to Hitwise research director Robin Goad, is likely driven by football fans.
Across all sites, Mr Goad says, Sundays proved most popular for shopping and social networking. The surprise relationship between social networking and adult-themed sites came last September, when total page visits for social networking sites for the first time eclipsed that of adult sites.
But it is not simply that viewers of pornography abandoned it in favour of online social interaction, according to Mr Goad.
"It seems that some of the less extreme content that can be found in the 'adult' category moved to these social sites," he says.
It is unlikely that there is a shift away from adult viewing overall, according to Mr David, just that it is finding different online outlets, and video-on-demand is a rising star among "content delivery" methods online.
"Adult entertainment is always at the forefront of technological advances on the internet, that's just fact.
"The reason that has been the case is because as humans we're instinctively drawn to that type of behaviour. I don't think there's anything particularly unusual in that in human terms. If anything, it sheds light on our true primal instincts."