Alice Giddings
Published December 1, 2025 6:00am
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The dark can disrupt a lot of our bodily functions (Picture: Getty Images)
There’s no challenge quite as insurmountable as dragging yourself out of your warm bed in the pitch black to squish onto a train and head to work.
Your body feels like it’s yet to wake up, and you can only hope you get a seat to rest your eyes for the next few stops.
Surely it can’t be good for us, all this constant waking up in the dark. So, Metro enlisted the help of a doctor to understand everything that happens to our bodies when we do.
Now we never want to wake up before sunrise again.
Why do we need light?
‘When you consistently wake up in the dark your body is being asked to override some very old biological rhythms,’ Dr Suzanne Wylie tells Metro.
‘Light is the primary regulator of your circadian rhythm, the internal clock that helps your body decide when to feel alert and when to feel sleepy.
Waking up in the dark can lower our mood significantly (Picture: Getty Images/Westend61)
‘When you wake before sunrise your brain does not receive that early morning light signal.’
Dr Wylie explains that without light we don’t get the rise in cortisol that makes us feel awake or the drop in melatonin that should happen to making waking up easier.
How does this make us feel?
‘This often leads to grogginess and slower cognitive processing, and many people describe feeling as if they are moving through the morning in a fog,’ the doctor adds.
But it’s not just fogginess that we’re lumbered with. Our mood and mental health are also sensitive to light.
‘Morning light exposure helps regulate serotonin which supports daytime mood and helps convert into melatonin at night,’ Dr Wylie, for IQdoctor, adds. ‘When people consistently wake in the dark they often report lower mood, irritability and reduced motivation.’
This is partly why seasonal affective disorder (SAD) becomes more common in the winter, when the nights are longer. But even in people without SAD, the lack of natural light in the morning can make the day ‘feel heavier and slower. ‘You may also find it harder to concentrate and feel mentally sharp,’ Dr Wylie explains.
You might think the dark would improve our sleep quality, but it can make it worse (Picture: Getty Images)
Sleep quality is harder
Pulling ourselves out of a deep sleep in the dark every morning can actually worsen our sleep quality.
‘Prolonged darkness outside normal sleeping hours can disrupt the circadian rhythm and alter the release of hormones such as melatonin,’ the doctor says. ‘This normally rises in the evening to promote sleep and falls in the morning to help us wake, extended periods of darkness can blur these signals, leading to more fragmented sleep, difficulty waking, and lighter, less restorative sleep.’
We may also feel more prone to the need to nap, as we get more fatigued, which means we then can’t sleep as well at night.
‘This can happen even if you think you’re getting enough hours,’ Dr Wylie says. ‘Poor sleep over time is linked to increased risks of high blood pressure, type 2 diabetes and weight gain because it interferes with metabolic regulation.
‘There is also some evidence that chronic circadian disruption may contribute to the development of mood disorders in susceptible individuals.’
What it's like to live in 24-hour darkness
Petri Kokkonen, from Vätsäri, spoke to Metro (Picture: Supplied)
Petri Kokkonen, 32, lives in the region of Vätsäri in Finnish Lapland, deep in the Arctic Circle. From October onwards, the region is completely covered in snow, the temperature can stay at -20C for days and, during the depths of winter, the sun doesn’t rise – at all.
At the end of November, Vätsäri is plunged into 24/7 darkness. The sun won’t make an appearance again until January 14, when it will rise for all of about 18 minutes.
‘The body can tell when the seasons are changing,’ Petri tells Metro. ‘Those first darker nights, I can tell I need more sleep than in the summer months.
Petri’s view during winter rarely changes (Picture: Supplied)
‘It can be difficult to really wake up in the morning. The body feels heavier and a bit frozen.
‘And I begin to get tired earlier in the evening once the days start to get shorter. There are days when I feel like I could sleep from 4pm.’
It’s a phenomenon referred to as ‘Polar Night Fatigue’, and is often experienced by those living within the Arctic Circle.
Some residents choose to use UV lights or supplements to combat the fatigue, but Petri staves off the tiredness by being in nature.
‘I spend my days outside and then during the evening, in my sauna,’ he says. He also adds that people power through by working during the winter months. After all, Christmas is big business in Lapland.
Your immune system
Our circadian rhythm also has a big impact on our immune system and its ability to fight things off.
‘Certain immune cells follow daily rhythms and are more active at specific times of day,’ Dr Wylie says. ‘Sleep disruption and a misaligned body clock can reduce the efficiency of the immune response.
‘In practice this can translate into feeling run down more easily or taking longer to recover from minor infections.’
To be clear, waking in the dark isn’t directly harming our immune system, instead it can be part of a pattern that weakens our immune resilience if our sleep quality is impacted.
Your bowel habits can be affected by the dark, too (Picture: Getty Images)
Digestion and metabolism
Metabolism is another thing than can suffer when waking up before it’s light, because again it relies on our circadian rhythm.
‘Many enzymes and hormones that regulate blood sugar, fat storage, and energy use are timed to follow a 24-hour cycle,’ Dr Wylie explains. ‘During the daytime, the body is primed to process and use energy efficiently, with higher insulin sensitivity and more active digestive function.
‘At night, the body shifts towards repair and storage, with reduced glucose tolerance and slower metabolism.’
So, when it’s dark when we’re awake our appetite regulation can be affected influencing weight gain and an increased risk of type 2 diabetes.
‘Your gut has its own clock and when your wake time is out of sync with dawn it can alter bowel habits, too,’ she says.
Is there a solution?
If you’re hoping there’s light at the end of the tunnel then, annoyingly, you’re out of luck.
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There’s not much we can do apart from try and expose ourself to light in the mornings.
‘For people who must wake early a practical solution is exposure to bright light as soon as possible after waking such as using a daylight lamp or getting outside once the sun rises,’ Dr Wylie says.
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‘This can help reset your internal clock and ease many of the effects described.’
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