Scientific reason why we always wake up five minutes before the alarm goes off

It's the ultimate frustration - you set your alarm for a certain time and your body decides to wake you up just a few minutes before - but there's a good reason why it happens

It can be incredibly frustrating to wake up before your alarm rings, particularly when you're hoping to enjoy those final moments of slumber.

Have you ever wondered why it happens though? You've set your alarm to go off at a fixed time, maybe it's a little later than you would have liked and you desperately want to have ever second of snooze you can get before the buzzer blares. But you don't even make it that far and, before you hear a peep out of your clock or phone, you're wide awake and checking out what time it is.

What makes it even worse, is that now you know you only have a few minutes left, the chances of you slipping back into the land of nod are close to none.

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Adding to the frustration, when it's the weekend or a holiday, you still find yourself waking up at an ungodly hour on autopilot.

So why is it so? Essentially, your body's internal clock is as efficient as your alarm in rousing you from sleep.

Your sleep-wake cycle is controlled by a protein known as PER. This protein level fluctuates daily, peaking in the evening and dropping at night.

When PER levels are low, your blood pressure decreases, heart rate slows down, and cognitive function becomes cloudier, making you feel drowsy.

By sticking to a consistent sleep schedule and waking up at the same time every day, your body learns to elevate your PER levels in anticipation of your alarm. Roughly an hour before you're due to wake up, PER levels rise, along with your body temperature and blood pressure.

In preparation for the stress of waking, your body releases a mix of stress hormones, such as cortisol. As a result, your sleep gradually lightens, which is why you often wake up before your alarm sounds.

Your body isn't a fan of your alarm clock. It's abrupt and disrupts all the careful preparation.

It undermines the purpose of a gradual awakening. So, to avoid being rudely interrupted, your body does something remarkable: It begins to increase PER and stress hormones earlier in the night.

Your body gets a head start so the waking process isn't abruptly halted. It's so accurate that your eyelids flutter open just minutes, or even seconds, before the alarm rings.