Why do I wake up right before my alarm?

There’s little research into how common the experience of waking up a minute or two before your alarm is and why it happens. But it seems to be “a genuine phenomenon” that many people report, according to Russell Foster, head of the Sleep and Circadian Neuroscience Institute at the University of Oxford in Britain.

In a telephone survey published in 1997, for instance, researchers from Iowa and Minnesota randomly interviewed 269 adults. About three-fourths of those interviewed said they sometimes woke up before their alarms, and just under one-fourth said they woke up so reliably that they never had to use an alarm.

After the research team published a newspaper ad asking for people who always or regularly woke up at specific times without using an alarm, they invited 15 of those respondents into a lab and tracked their sleep for three nights. They found that five of the 15 awoke within 10 minutes of their target wake-up times all three times.

Timing is everything

Nobody knows exactly how or why the body is able to do this, but researchers say that our biological clocks, which keep track of time, have something to do with it.

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Just above the optic nerve in the brain is a master clock called the suprachiasmatic nucleus, says Dr Ravi Allada, a neurobiologist who specialises in sleep and circadian rhythms at Northwestern University.

This clock synchronises and coordinates our body’s circadian rhythms, which help us prepare for things that happen at various times of day – such as falling asleep at night and waking up in the morning.

One way our body does this is by sensing the levels of light around us, Foster says. Special cells in our eyes detect changing light levels, such as right before and at dawn – even through our eyelids when our eyes are closed, he says. These cells probably don’t tell our bodies precisely what time it is, but they may communicate that we’re approaching the time we normally get up.