How hidden 'overtiredness' is ruining your sleep – and how to fix it

You know the feeling: you’ve had a hard day, you’re mentally and physically defeated, and, overwhelmingly, you just want to curl up and sleep.

However, your brain, the Universe's most powerful biological supercomputer, decides it's pranking time. Instead of letting you nod off, it leaves you staring at the ceiling, thoughts speeding through your mind like a cheetah on roller skates.

But why does this happen? How come your mind stops you from sleeping exactly when you need it the most? The answer: it’s likely you’re overtired, effectively too tired to fall asleep.

If you’ve heard the term before, it’s probably been used to describe a baby. That's because when an infant has been up for longer than their little bodies can manage, they enter a state of 'overtiredness' where stress and sleep difficulties ensue.

However, the same problem can also occur in adults when unchecked emotions stall your body’s default shutdown programme. Worse still, if you're persistently overtired, getting to sleep can get harder and harder.

Fortunately, there are ways you can break the cycle. Below we not only explain what overtiredness is, but also three easy, science-backed steps that will help put it to bed for good.

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How being overtired ruins your sleep

Being overtired is a cruel paradox. While you may feel exhausted from physical and mental chores, your brain is actually overstimulated and in a state known as hyperarousal. Not like that: being aroused in this instance just means your mind is on high alert and hasn’t had the chance to unwind before bedtime.

It’s this state of thinking that halts some of the key functions that allow your body to sleep. In particular, the build-up of sleep pressure.

As a process, sleep pressure is largely what it sounds like. When you’re continually awake during the day, various neurochemicals and hormones in the brain, such as adenosine, increase in concentration. It’s their build-up that largely drives your need for sleep.

“Interestingly, over the same time as sleep pressure builds, the brain can become more and more excitable,” says Matt Jones, professor of neuroscience at The University of Bristol.

“The neurons in your cerebral cortex [the outer layer of your brain] tend to fire increasingly frequently over the course of an extended period of wakefulness.

"A key theory is that sleep resets your sleep pressure – sleep effectively stops the brain from getting more and more excitable and metaphorically exploding!”

Read more:

• Can’t stop your brain racing at 3am? Try these suggestions from a GP
• Why do I always find things to do late at night?

As you might guess, being in a state of hyperarousal, with thoughts from the day racing through your mind, royally screws this system reset.

Specifically, it impacts a small part of the brainstem called the locus coeruleus.

“Activity in this brain region needs to be slow to enable us to transition into sleep. But during hyperarousal, activity here is abnormally high. And that resists the mechanisms that allow sleep pressure to increase and let us get off to sleep,” says Jones.

Worst still, if you are regularly overtired and miss out on sleep, your brain may become more stimulated by troubling thoughts the next night.

One 2019 study found that people who suffer from insomnia were significantly more likely to mull over a recent embarrassment at night than healthy sleepers.

And, as one Dutch study showed, insomnia sufferers can be hypersensitive even to the sound of their own heartbeat, which may keep them awake for longer.

“Rested brains are good at ignoring things that happen all the time but have no real consequence. But if you suffer from insomnia, you’re less able to let go – consciously or unconsciously – of irrelevant information. That accumulates a massive burden on the brain,” explains Jones.

How to stop being overtired

In a nutshell, if you’re overtired and key brain regions are still in a state of hyperarousal when your head hits the pillow, you simply haven’t processed everything important from your day.

As Dr Alex Scott, lecturer in psychology at Keele University, explains, this is actually extremely common: “As humans in today’s society, we are normally quite bad at regulating our emotions and processing things that have happened to us. We simply don’t get the opportunity.

“This means at the very end of the day we’re left unable to think about our emotions in a positive way. Instead, we blow things out of proportion and ruminate over our worries in bed.

He adds: “Ruminating is a quick fix that we use to try and feel in control, but we're not really positively processing these thoughts – it’s not conducive to good mental health.

"The more tired we get, we’re more likely to use a maladaptive strategy to tackle our worries, like ruminating or blaming others.”

So, if ruminating isn’t likely to terminate your overtiredness, what will? Scott has three key strategies you can use.

1. Stop counting sheep

The frustrating truth: you can’t will yourself to sleep. In fact, the more effort you put in, the harder it will be to drift off. That's why strategies like counting sheep have been shown to not help you get to sleep any faster.

What can help, however, is accepting this fact. “We need to acknowledge that sleep is an automated process. It won’t happen if you try and make it happen,” says Scott.

Instead, focus on what you can control: processing your emotions with a worry diary (see next step).

Read more:

• Why do I always come up with my best ideas when I’m trying to get to sleep?
• What’s the best thing to do when you can’t sleep?
• Poor quality sleep may scupper our attempts to keep weight off

2. Keep a worry diary

We get it: penning a worry diary sounds like a prospect deserving of your eye rolls. But, according to Scott, this simple exercise regularly betters the shut-eye of patients with sleep problems.

Writing the diary is simple enough. Before bed, list your worries on a page, whether it’s related to work, health, your social life – whatever. And that’s pretty much it.

The act of writing down these worries itself may help reveal how much these anxieties aren’t rooted in reality. For other worries, you may want to write down a quick action plan for how you’ll tackle them tomorrow, a practice that, as Scott says, will help you temporarily put the problem aside.

“In no way am I saying that once you’ve put them down on the page, your worries will be solved. When you turn the lights off and your bedroom is quiet, those thoughts are going to be there,” he says.

“This is more a tool to force you to process your emotional responses around the things that are keeping you awake.”

And if your worries are still running rampant in your mind come 2am? Rinse and repeat: if you can’t get to sleep after 15 minutes, get out of bed and find a peaceful part of your home to write more worry diary entries, covering the same ground if needed.

“One of the worst things you can do is stay in bed tossing and turning,” explains Scott.

“It’s all about managing what's called 'stimulus control'. This basically means it's a good idea not to associate your bed with too much worrying – that can lead to more sleep problems.”

3. Set a bedtime timer

How do you make sure you have time to process your day? Set an alarm for it – preferably an hour before bed. According to Scott, Using this time to unwind and relax will help you fortify your mind against emotional exhaustion.

“Whatever works in this hour will depend on the individual,” he says. “It might be reading a book, it may be doing some mindfulness or writing a worry diary.

“But the key is safeguarding time before bed. It's to make sure that the winding down process is not occurring when you're trying to actually sleep.”