There's no denying that the invention of electronic clocks has made the process of waking up in the morning a little less traumatic. In the old days the only way to wake up on time was to invest in a clockwork alarm clock, usually featuring two sizeable bells on top which would be struck by a rapidly oscillating hammer at the time you chose to be woken. The noise emitted by these clocks - as it appears to someone who is happily slumbering - can best be described as a cross between an air raid siren, a fire alarm bell and someone shouting very loudly in your ear. Statistically it appears the most popular time to die is 2 a.m., but this seems hard to believe when one considers the potential for heart attacks provided by the insistent ringing of an alarm clock at 7 o'clock.

The electric clock radios now found on many people's bedside tables usually offer a gentler start to the day. You can still, if you are a heavy sleeper, be woken by the clock's buzzer - a sound similar in many particulars to the horn of the Queen Mary on a foggy day in the Channel. But since the radio can also be used as a wake-up signal, there is the option of being woken by the sound of music - though not necessarily Julie Andrews' dulcet tones - or the sound of politicians being baited by morning news show presenters. And, most significantly of all, these clocks almost all feature a snooze button.

It was General Electric that marketed the first clock with a snooze feature as long ago as 1956. You hit a button on top of the clock or clock radio - usually it's a large button that can be found be even the drowsiest hand - and the alarm is silenced for a few minutes, allowing you to wake up gradually.

Surveys indicate that people use the snooze alarm an average of three times before eventually getting out of bed. Given that the most common time interval allowed between alarms by a snooze button is nine minutes, that equates to 27 minutes of indolence per person per day. It also suggests that, unless people are arriving at work very late every morning, they must be setting their alarm for a time well before they actually need to get up. Is this logical? Not really.

Neither, apparently, is that nine-minute snooze interval. Many theories have been advanced as to why the interval might be nine minutes, including one that claims psychologists have calculated this to be the maximum time a person can safely be allowed to drowse before he or she will relapse into a deep sleep. But the most likely explanation appears to be that the manufacturers of early snooze clocks selected a time that was roughly between nine and ten minutes, and that the designers of digital clocks came to accept this nine-minute interval as an industry standard.