A popular view of online communities is that they transcend time and place. As threads and comments are posted during the circadian cycle, however, participants will see different (new) threads as they arrive, which then affects who interacts with whom and the social ties that form.
A case-study of the Hacker News community was conducted to measure these effects. Strong time-pressure effects were found at the thread-level. For social ties statistically significant effects were found as well; especially for users at the edge of the network. Even the two-week gap between the introduction of daylight savings time in the US and UK had an impact.
These findings indicate that online communities may not be as global as generally believed, and might limit the validity of purely social interpretations of online reply structures.