Added to this is the time people spend with their inbox. A July 2006 study by ClearContext, an email management tools vendor, surveyed 250 users and discovered that 56% spent more than two hours a day in their inbox (bit.ly/email4). Most felt they got too much email - by January 2008, 38% of respondents received more than 100 emails a day - and that it stopped them from doing other things. Karen Renaud, a lecturer at the University of Glasgow, Scotland, and her colleagues at the University of the West of Scotland discovered that email users fall into three categories: relaxed, driven and stressed. "The relaxed group don't let email exert any pressure on their lives," Dr Renaud says. "They treat it exactly the way that one would treat the mail: 'I'll fetch it, I'll deal with it in my own time, but I'm not going to let it upset me'." The second group felt "driven" to keep on top of email, but also felt that they could cope with it. The third group, however, reacted negatively to the pressure of email. "That causes stress," says Dr Renaud, "and stress causes all sorts of health problems."

Dr Renaud's team discovered that while 64% of respondents claimed to check their email once an hour, and 35% said they checked every 15minutes, they were actually checking it much more frequently - about every five minutes. For some people, checking email is no longer a conscious and deliberate act, but a compulsion they are barely aware of (bit.ly/email5). Tom Stafford, a lecturer at the University of Sheffield, England, and co-author of the book Mind Hacks, believes that the same fundamental learning mechanisms that drive gambling addicts are also at work in email users. "Both slot machines and email follow something called a 'variable interval reinforcement schedule' which has been established as the way to train in the strongest habits," he says.

"This means that rather than reward an action every time it is performed, you reward it sometimes, but not in a predictable way. So with email, usually when I check it there is nothing interesting, but every so often there's something wonderful - an invite out or maybe some juicy gossip - and I get a reward." This is enough to make it difficult for us to resist checking email, even when we've only just looked. The obvious solution is to process email in batches, but this is difficult. One company delayed delivery by five minutes, but had so many complaints that they had to revert to instantaneous delivery. People knew that there were emails there and chafed at the bit to get hold of them. Another solution might be the notification system Growl (growl.info), which puts up a brief message on the screen with details such as the sender and subject line while the user is in other programs. Presently only available for Mac OS X, a version is being tested for Windows though this, of course, causes the interruptions you are trying to avoid. Companies are beginning to take these problems seriously, although the "no email days" favoured by Deloitte and Intel have not proved effective. Deloitte's "no email Wednesday" was abandoned after a month (bit.ly/email6) and Intel found that there was a "clear incompatibility" between the need of the pilot group to communicate asynchronously with colleagues and the avoidance of email for a whole day (bit.ly/email7). No-email days don't work, says Dr Stafford, "because they don't help people to change their behaviour while they are actually using email. Once your email is back, you're going to respond to it in the same old ways unless you replace your bad habits." It's better to replace email with more appropriate tools. Roo Reynolds, a "metaverse evangelist" who is joining the BBC to work with social media, has moved away from email for everything but the most formal communications. "I use other tools ... I've got a whole set of contacts who love Twitter and if I want to reach them quickly then that's where they'll be."

Mr Reynolds has even begun to think of email as rude and invasive, preferring to use tools such as Twitter and Flickr. He also uses social networking sites such as Dopplr, which tracks people's travel, to find out if they are away before he contacts them, and status alerts from instant messenger or Twitter to help him decide if now is a good time to interrupt them. Other tools, such as blogs and wikis, have decreased the amount of email that he sends and receives, while RSS feeds and recommendations from friends and colleagues allow him to keep abreast of the most important news. For a tool that business depends so heavily on, we put little thought into how we use email. Dr Karol Szlichcinski, a business psychologist, recommends providing guidelines and training to give people "ways of reducing the disruption caused by email, ways of managing email so that it doesn't run your day. Organisational norms build up, and people come to expect others to answer emails within a given timeframe, whether that email is important or not."

We may think email is simple, but its ease of use is deceptive. For many, it's a boon, but for an increasing majority it's the tail that wags the dog. Keeping control of the inbox If you find your mouse straying towards the "check email" button far too often, try these tactics:

- Turn off intrusive alerts. Anything that pops up, flashes, or goes "ding!" will interrupt you when you're trying to focus and will trigger a response to check your email. - Set your email client to display just the title and first few lines of the email, so you can easily decide if it is important enough to deal with right now.

- Use other tools. Twitter and instant messaging (IM) are better for asking short questions of chosen groups. Wikis are better for collaborating on documents. Blogs are better for publishing information and having informal conversations. - Send fewer emails. Do you need to hit "reply to all"? - Schedule your email. Set aside time each day to deal with your inbox and ignore it for the rest of the day. Most people check first thing in the morning and late afternoon.

Suw Charman-Anderson is an expert in collaboration and communications

- THE GUARDIAN