Research into emails sent by Enron staff before the company's collapse in 2001 has yielded some intriguing results. About a month before key events happened in the history of Enron, like the resignation of the CEO, email patterns drastically changed.

Normally, the amount of email "cliques", where everyone emailing knows everyone else, is fairly low in an organisation. However, before dramatic events occurred, the number of these email groups shot up from 100 (among 15,000 employees) to almost 800.

The researchers behind the work, Ben Collingsworth and Ronaldo Menezes at the Florida Institute of Technology in Melbourne, say that as a company becomes more stressed, people begin to only talk to people they trust. They presented their findings at the International Workshop on Complex Networks, held in May 2009 in Catania, Italy.

Few similar studies have been carried out, due to the difficulty of obtaining data - email logs are rarely made public. However, the findings could prove valuable for HR departments at large companies.