You may be dealing with something called sleep inertia (Picture: Getty)

Ever wake up from a nap feeling disoriented and groggy?

We’ve all been there.

You’re feeling a little sleepy. So you get back into bed, draw the curtains to block out the daylight and set a timer.

Half an hour later, the alarm goes off, and you wake up, expecting to feel refreshed and full of life, only to realise you actually feel even more tired and worse than before. 

We all know sleep is vital for good health, so why do we sometimes feel worse after sneaking in a quick 30 minutes of shut-eye?

‘It is common to feel groggy or disoriented after waking up from a nap,’ explains Nicole Eichelberger, a sleep expert and consultant at Matteressive.

This is due to a phenomenon known as sleep inertia.

While the feeling doesn’t tend to last too long, it can cause people to feel ‘heavy’ upon waking, according to Healthline. It is more common for people who have alternate and irregular sleep schedules, such as shift workers and nurses, and typically lasts for 15 to 60 minutes, the Sleep Foundation explains.

For those who experience this feeling for longer, you may have ‘prolonged sleep inertia’. 

If it causes significant disruption in your daily life, it may be best to seek medical advice.

Why does it happen?

‘Sleep inertia is the result of your brain and body transitioning from a state of sleep to a state of wakefulness,’ adds Nicole.

‘It can be caused by several factors, including the length of your nap, the stage of sleep you were in when you woke up, and your overall sleep patterns.’

While the biological reasoning remains unknown, the Sleep Foundation notes that some researchers have a theory suggesting that sleep inertia can be a ‘protective mechanism’ whereby the body is trying to maintain sleep following unwanted awakenings.

How to avoid or reduce sleep inertia after a nap

Waking up feeling worse than before may put you off having a nap but rest assured, there are actually benefits to having a little extra sleep during the day.

‘Having a nap can improve memory function, job performance, improve sleep deprivation if you have not been sleeping well, lower blood pressure and help with stress relief,’ NHS and private GP Dr Hana Patel explains.

So if you’re going to snooze during the day, here’s how to do it well.

Keep your naps short

‘Napping for more than 30 minutes can lead to sleep inertia,’ explains Nicole. ‘If you need to nap, try to keep it to 20-30 minutes.’

Dr Hana warns that a study from the European Society of Cardiology has shown that regular naps of over 60 minutes can increase the likelihood of cardiovascular diseases, metabolic syndrome, and diabetes.

Wake up during a lighter stage of sleep

Nicole suggests trying to use an app or device that tracks your sleep stages and wakes you up during a lighter stage of sleep. This can help you feel more alert and refreshed after a nap.

Establish a consistent sleep schedule

‘Maintaining a consistent sleep schedule can help regulate your body’s natural sleep-wake cycle and reduce the likelihood of feeling groggy after a nap,’ adds Nicole.

Dr Hana also suggests considering the environment you sleep in.

‘A good environment for sleep is important so that it is quiet, dark, and a comfortable place, such as your own bed or a comfortable chair,’ she says. 

‘Also factor in time to recover and fully wake up after your nap to help put you in the best frame of mind to continue your day.’

Avoid napping too late in the day

‘Some people may find that napping at certain times of day is more refreshing than others,’ Nicole says. ‘Experiment with different times to see what works best for you.’

But she warns that napping too close to bedtime can interfere with your ability to fall asleep at night, which can contribute to sleep inertia. She recommends trying to avoid napping after 3pm.

‘Between 1pm to 3pm is the best time to nap, as this is a natural time when we feel tired and have reduced energy in the day,’ suggests Dr Hana.

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Drink caffeine

Caffeine gets a bad rep when it comes to sleep, but Nicole says it can can help reduce sleep inertia by stimulating your central nervous system and making you feel more alert.

She adds: ‘Just be sure to consume it in moderation, as too much caffeine can interfere with sleep later on.’

If you find yourself feeling awful after every nap, it may be best to talk to your GP.

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You may be dealing with something known as sleep inertia.