Sleeping for 8 hours but waking up exhausted? This popular household item could be to blame — here's how to fix it in 5 seconds

The lefthand side of the image shows a dark haired woman lying in bed with with her eyes open, while on the right we see a woman with long dark hair wearing grey pyjamas opening a pair of curtains.
(Image credit: Getty Images)

Blackout curtains are an excellent solution to blocking out early morning sun and ambient light pollution. However, sleep experts are warning that they could be the reason that you're waking up exhausted, despite clocking up plenty of rest.

By blocking out the morning sunshine, we're missing out on a key wake-up cue — which leads to circadian rhythm disruption and morning fatigue, explains physician Dr. Fábio Luiz Vieira.

"Sleep quality is largely determined by darkness at night and light in the morning," says Dr. Vieira, founder of My Brazilian Doctor. "Waking in darkness can delay circadian signaling and reduce morning alertness."

To find out more, I quiz the experts on why waking up in total darkness can leave us feeling exhausted. Plus, I find out the quick fix for an instant morning energy boost.

Key take-aways: At a glance

  • Studies show that blackout curtains create a dark environment to boost melatonin, a hormone which helps us fall asleep.
  • However, blackout curtains block out morning light, which the body uses as a signal to produce cortisol, a hormone that help us feel awake and alert upon waking.
  • When cortisol is reduced due to a lack of daylight in the morning, this can lead to morning fatigue, plus a delayed wake-up time and bedtime.
  • To increase alertness in the morning, aim to open your blackout curtains immediately upon waking, urge experts.
  • Using a sunrise alarm clock has been proven to increase cortisol and serotonin production, a get-up-and-go hormone combination.

How blackout curtains can cause morning tiredness

A woman lies asleep in a bed that has all white bed linen. In the background are curtains that are slightly open, letting sunlight in.

(Image credit: Getty Images)

Research has shown that those who sleep in a room affected by light pollution are more likely to experience sleep deprivation and anxiety. Meanwhile, a 2021 study found that being exposed to even a small amount of light while sleeping can lead to more nighttime awakenings.

Waking up in the dark means our bodies aren’t given the signal to stop producing sleep hormones

James Wilson, Bensons for Beds

That's where blackout curtains and blinds can step in. Blackout curtains have become a popular sleep tool to reduce the affects of light pollution, creating a dark environment free of sleep-disrupting light.

"Blackout blinds can be beneficial, particularly if you live in environments with lots of light exposure," says James Wilson of Bensons for Beds.

"If we’re woken in the night for whatever reason, the complete darkness helps us to settle back into to sleep more easily than if we were exposed to light," the sleep practitioner adds.

However, while blackout curtains create a sleep-inducing environment at night, they can also create an environment that decreases energy levels in the morning.

Research has found that the addition of blackout curtains can disrupt our natural circadian rhythm, which is our body's internal clock. Study participants reported feeling more alert at night and sluggish in the morning when sleeping in a room with blackout curtains.

This lead to an out-of-sync sleep schedule, characterized by delayed wake-up times and bedtimes.

But why does waking up in darkness cause morning tiredness? Dr. Vieira explains that it's all to do with how darkness increases the production of sleep-promoting hormone melatonin.

"Light is the primary cue for suppressing melatonin and activating the brain’s wake systems," the doctor explains.

Studies have even highlighted how our biological clock relies on light to know that it's daytime, with sunlight boosting cortisol, a hormone that promotes energy and alertness.

According to Wilson, blackout curtains remove a natural (and crucial) wake-up cue.

"Waking up in the dark means our bodies aren’t given the signal to stop producing sleep hormones and to start producing cortisol, which helps us start the day," he warns.

3 quick and easy ways to boost morning energy

While blackout curtains can play havoc with your sleep schedule, Hannah Shore, Head of Sleep Science at MattressOnline, highlights how they're still important especially during the summer months.

"If we don’t have these, we would be waking up when the sun rises, which can be as early as 4:30am in peak summer," she warns.

Luckily, sleep experts say that there are quick and easy ways to enjoy the sleep-promoting benefits of blackout curtains at night and in the early hours of the morning, without skipping the energy-boosting sunlight when you need to get up.

1. Open your curtains as soon as you wake up

A woman stands by a window of a sunlit bedroom in the summer

(Image credit: Getty Images)

The quickest and easiest way to feel energized in the morning is to head over to your window as soon as you wake up and draw back the curtains.

"Blackout curtains are best combined with intentional morning light exposure, such as opening curtains immediately upon waking, to maintain circadian alignment," advises Dr. Vieira.

In fact, Ruth Jones, a Senior Sleep Writer here at Tom's Guide, swears by this five-second morning habit.

"I needed blackout curtains to fall asleep in a room plagued by streetlights, but the lack of morning sunlight left me groggy and fatigued," says the sleep writer.

To remedy her morning fatigue, Jones says she would open her curtains as soon as her alarm beeped.

"At the first chime, I'd fling my curtains back before hitting snooze, allowing the natural daylight to slowly rouse me; I was awake and alert before the second alarm could start," she tells me.

2. Invest in a sunrise alarm

The Lumie Bodyclock Luxe 700FM sunrise alarm clock lighting a dark room with a sunrise-mimicking glow.

(Image credit: Future)

After testing my first wake-up light for my Lumie Bodyclock Luxe 700FM sunrise alarm clock review, I am now someone who preaches about how refreshing it is to wake up to a gentle, gradually-brightening light instead of a harsh iPhone alarm.

Sunrise alarms work by mimicking a sunrise, and this dawn simulation has been shown to increase cortisol.

"If you're using blackout blinds, I always reccomend coupling them with one of the best sunrise alarm clocks to wake up by light as well as an audible alarm," advises Wilson.

3. Go for a walk in the first hour of the day

A couple go for a morning walk through a sunny park.

(Image credit: Getty Images)

Another morning habit I swear by is a quick walk in the morning light. Not only is a morning stroll a great way to get a boost of Vitamin D, it's also proven to be a great way to boost sleep quality and increase energy levels.

To feel more refreshed in the morning, all you need to do is head out the door between 30 and 60 minutes after your alarm.

"Getting access within the first hour of waking every day, so long as it is the same time, will help to set your body clock, which in turn can make it easier to fall asleep and wake up in the future," says Shore.

3 products that boost morning energy

Silk Road Organic   Peppermint Essential Oil Roll-on
Silk Road Organic Peppermint Essential Oil Roll-on: was $10.95 now $9.95 at Amazon

Studies have shown that peppermint oil can increase energy and focus, helping both physical and mental performance. With a 4.2 star rating on Amazon, the Silk Road Organic Peppermint Essential Oil impressed customers with its fresh scent and cooling feel. Try applying this organic aromatherapy roller on your pulse points to boost alertness when you wake up.

JALL Sunrise Alarm Clock
JALL Sunrise Alarm Clock: was $52.98 now $32.88 at Amazon

Some sunrise alarms come with a hefty, premium price tag. However, other sunrise alarms can offer the same energy-boosting benefits but for a budget price. Take, the JALL Sunrise Alarm Clock. It's an Amazon bestseller, always discounted below $35, and impressed us during testing for our JALL Wake-Up Light Sunrise Alarm Clock review.

Yogi  Sweet Tangerine Positive Energy Tea
Yogi Sweet Tangerine Positive Energy Tea : $4.46 at Amazon

Want your morning caffeine fix with a traditional, fruity twist? Try this sweet tangerine tea from wellness brand Yogi. It's vegan and organic, and uses a blend of herbs traditionally used to support focus and energy levels. With a 4.7 star rating, customers praise the refreshing flavor and how it boosts mood and energy.


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Frances Daniels
Senior Sleep Staff Writer

Frances Daniels is a PPA-accredited journalist and Sleep Staff Writer at Tom's Guide with an MA in Magazine Journalism from Cardiff University. Her role includes covering mattress and sleep news and writing sleep product reviews and buyer's guides, including our Best Hybrid Mattress 2025 guide. She is interested in the relationship between sleep and health, interviewing an array of experts to create in-depth articles about topics such as nutrition, sleep disorders, sleep hygiene, and mattress care. She is also our specialist on mattress toppers — producing bed topper reviews and taking care of our Best Mattress Toppers 2025 guide — and leads content relating to fiberglass-free beds for a non-toxic sleep. Outside of Tom's Guide, she has written for Ideal Home and Marie Claire.

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