Why we wake up minutes before the alarm clock goes off – 7/3/2023 – Equilibrium

Sometimes I wake up a minute or two before my alarm goes off. This is normal? Why does my body do this?

There is little research on how common this experience is and why it happens. But it seems to be “a real phenomenon” that many people mention, according to Russell Foster, head of the Institute of Sleep and Circadian Neuroscience at the University of Oxford in Britain.

In a telephone survey published in 1997, for example, researchers from Iowa and Minnesota (United States) randomly interviewed 269 adults. Around three-quarters of respondents said they sometimes woke up before their alarm went off, and just under a quarter said they woke up so reliably that they never needed to use an alarm clock.

After the research team published an ad in the newspaper asking about people who always or regularly woke up at specific times without using an alarm clock, they invited 15 of these respondents into a laboratory and monitored their sleep for three nights. They found that 5 out of 15 woke up 10 minutes before their waking times on all three nights.

Time is everything

No one knows exactly how or why the body is able to do this, but researchers say it has something to do with our body clocks.

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

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

One way our bodies do this is by sensing the light levels around us, says Foster. Special cells in our eyes detect changes in light levels, such as just before and during dawn — even through the eyelids when we have our eyes closed, he says. These cells probably don’t tell our bodies exactly what time it is, but they can communicate that we’re approaching the time we normally wake up.

This triggers changes — like increases in the hormones cortisol and adrenocorticotropin, as well as blood pressure, Foster says — that help us prepare for activity.

What about times when you woke up just before the alarm clock but it was a much earlier time than your body is used to, like catching a flight or making an important appointment?

Instead of waking up based on time, points out Allada, our bodies can wake up based on how long it’s been since we went to bed, working almost like an hourglass. If we go to sleep knowing we have to wake up in four hours, something might help wake us up after that time.

When things go wrong

If our bodies are so good at perceiving time, why don’t we always wake up before the alarm clock? And why do some people never wake up before the alarm clock?

Foster isn’t sure. It’s possible that when you’re extremely tired, your body’s need for sleep overwhelms your body clock, he indicates.

Or sometimes, if you feel nervous about waking up on time, stress can cause you to wake up earlier than you’d like, says Allada.

The bottom line is that there are still far more questions than answers about why and how our bodies sometimes wake us up before our alarm clock.

But to increase the likelihood that you’ll wake up on time on your own, Foster suggests, it can be helpful to set your alarm for the same time each day, so your body gets used to waking up at a regular time.

Translated by Luiz Roberto M. Gonçalves