A PopCap Games survey released today sheds new light on the demographics of social gamers, concluding that the number of people who play social games in the U.S. and U.K. alone is likely somewhere around 100 million. Much like casual games before them, social games are thought to represent a huge opportunity to reach millions of consumers who historically have not played videogames before. Not surprisingly, Facebook is leading the charge as the most popular social gaming destination.

The survey, which targeted approximately 1,200 people in the U.S. and U.K. who played games on social networking such as Facebook and MySpace, found that the vast majority (95%) played more than once per week. Nearly two thirds said they played at least once a day, and for one in ten respondents an average play session lasted three hours or more.

“This study establishes social games as a fast-growing and quickly maturing pastime for an enormous portion of the population,” said Robin Boyar, founder and principal at Thinktank Research, in a prepared statement. “And with more than 80% of social gamers stating that playing social games strengthens their relationship with friends, family and colleagues, social gaming reinforces the core appeal of social networks.”

More than half (56%) of the social gamers surveyed said they had been playing social games for more than a year. About one quarter (26%) said they were new to social gaming, having only started playing within the last six months. About one third (35%) of social gamers say their consumption of social games has increased over the past three months, compared to 10% who said it had decreased.

When it came to playing preferences, Facebook was far and away the most popular destination for social gamers, with 83% of social gamers citing Facebook as a place where they went to play social games. MySpace was a distant second with 24%, followed by Bebo (7%), Friendster (5%), Hi5 (4%), Orkut (2%) and Netlog (2%).

Interestingly, the survey revealed that roughly half of the time social gamers logged into social networks it was specifically to play games. While on the network, social gamers spent roughly 40% of their time playing games, followed by chatting with and messaging friends (17%) and playing non-social (solo) games (15%).

When asked why they played social games, the most popular answer was “fun and excitement” (53%), followed by stress relief (45%), “competitive spirit” (43%) and “mental workout” (32%).

As annoying as those endless Facebook Friend notifications about lost sheep, lonely cats and mafia hitmen are, it looks like they’re actually pretty good at influencing people. More than half (57%) of respondents said that they heard about new social games through a combination of receiving alerts from online friends who were also playing the game, word of mouth, and seeing ads promoting the game from within the social network itself. (Search engines influenced 27% of respondents, followed by ads on non-social gaming sites [18%]).

Roughly half (53%) of players said that they had earned or spent virtual currency in a social game, but only 28% have purchased virtual currency with real-world money, and only 32% have purchased a virtual gift. Nearly a third (32%) of social gamers said they’re likely to purchase virtual items with real-world currency.

One of the survey’s few disheartening findings was that one full quarter (25%) of respondents said they had been misled by an ad or “special offer” tied to a social game they’ve played, which underscores the fact that in spite of how potentially lucrative as the social games sector may be, the industry still has some maturing to do.

However, the survey also highlighted one of the great strengths of social games: that they allow players to build and strengthen personal relationships with each other. Sixty-two percent of respondents said they played social games with real-world friends, while a further 56% played with friends they had made online. Nearly half (43%) of social gamers say they also play social games with their parents, children, and/or other relatives.

Sixty-two per cent of social gamers agreed that social games made it easier for them to reconnect with old friends, work colleagues, classmates and even old girlfriends and boyfriends. A similar percentage (63%) said that social games have been a source of new friendships and 70% say that social games make them feel more connected to other members of their social networks.

“I have family spread out all over the country, and we only get to see each other once a year, at Christmas,” one U.K.-based survey respondent wrote. “The gaming gave us something to connect over and helped begin discussions, even carrying over the Christmas period. It helped the older cousins interact more with the younger cousins.”