Sleep Cycle is a Swedish-designed iPhone app that turns your mobile into a sleep-tracking device. It works using a sensor in the iPhone – called an accelerometer – that enables it to monitor movement.

Depending on what phase of sleep we're in, our bodies behave differently: when we're sleeping most soundly, we're most still; during the dreaming (or REM) phase we twitch around more; and as we approach wakefulness we become even more restless.

Sleep Cycle uses these fluctuations to create a nightly record of your sleep, which it presents to you each morning in the form of a graph. More remarkably still, it uses this information to decide (within a half-hour time frame) when you've reached the optimal point in your cycle to wake up. Then it assists you back to consciousness with soothing music.

Since it was launched last summer Sleep Cycle has become the bestselling paid-for app in several countries, including Sweden, Germany and South Korea. Does this reflect the fact that those nations take sleep more seriously than we do? There is some evidence, after all, that the British aren't very good at sleeping. The Clinical Sleep Research Unit at Loughborough University found that nearly a third of us have "significant sleep difficulties". There has been talk of an "insomnia epidemic". As a nation it seems we'd be less anxious, less depression-prone, if we mastered the trick of easeful sleep.

Could Sleep Cycle, which is both simple to use and cheap (it costs 59p), help? Last week I used it for three successive nights. The results were mixed. It was certainly fascinating to gain an insight into my nocturnal habits (what happens to us during sleep, after all, is the one part of our lives that is usually totally closed to us). Impressively, it really could tell when during the night I'd been awake. Yet I also found it oddly distracting. You're required to place the phone on the corner of your mattress, and simply having it there, knowing that it was monitoring me, made me feel strangely self-conscious.

For the first time in ages I started finding it difficult to fall asleep; and the knowledge that my graph the next morning would be disappointing only made the problem worse. Rather than become a better sleeper, Sleep Cycle seems to have turned me (temporarily I'm sure) into an insomniac