I kept waking up 2 hours before my alarm because of this common bedroom mistake — here's how I fixed it instantly

(Image credit: Future) We've all experienced that bleary-eyed panic of suddenly waking up and thinking you've missed your alarm — only to discover that it's 5 a.m. and you don't need to get up until another two hours.But for the past few weeks I've waking up hours before my sunrise alarm most mornings, usually between 4 a.m. and 5 a.m., leaving me crawling through each day in an exhausted fog. I was at a loss as to why this kept happening, until a new study revealed the culprit. Here's the surprisingly small thing that kept waking me up way too early, plus the cheap, easy fix that helps me stay asleep all night.Key takeaways from the new study:Researchers at Tulane University have found that light exposure (over 3 lux) from electronic products such as chargers and stand-by lights can cause shorter, disrupted sleep and body clock changes.People with the brightest bedrooms at night slept about 48 minutes less each night (6.9 hours) compared to people who slept in total darkness (7.7 hours).This shorter sleep duration can change the way the heart functions, leading to cardiovascular damage over time.To limit nighttime light exposure, experts recommend covering lights from electronics with LED light-blocking stickers, using blackout curtains, and wearing eye masks.Why I kept waking up hours before my alarmAccording to a new study conducted by researchers at Tulane University, exposure to light at night can shorten our overall sleep duration. This reduced sleep duration over a long period of time can lead to impaired heart health, say scientists — and 50% of that cardiovascular damage is caused by light exposure cutting sleep prematurely short.The study also found that people with the brightest bedrooms at night slept about 48 minutes less each night (6.9 hours) compared to people who slept in total darkness (7.7 hours). (Image credit: Shutterstock)When I first read the results of this study, I found them fascinating — but couldn't see how they were applicable to me. After all, I keep my blinds closed, I don't use a night light, and I put my phone on Sleep Mode so my phone doesn't light up with notifications throughout the night.However, when I found myself waking up at 5 a.m. again, I looked around the room and spotted the culprit: the light from my laptop charger, making my room look as if it were bathed in blue light.I must not have spotted the charger's glow when I first turned off the bedroom light, but I could now see the charger light's full disruptive impact once my eyes adjusted to the dark.Get instant access to breaking news, the hottest reviews, great deals and helpful tips.How does bedroom light affect sleep and health?The same study also found that the cardiovascular damage caused by nocturnal light exposure also stems directly from the artificial light disrupting the body's circadian rhythm.However, the main ramification of light exposure remains shorter sleep, with exposure to light at night (>3 lux) suppresses melatonin, resulting in shorter sleep duration which in turn leads to "cardiac remodelling".“This is the first study of its kind, and it shows that exposure to higher levels of light at nighttime is linked to cardiac remodelling," says Professor Lu Qi, who led the groundbreaking study. (Image credit: Future)"Cardiac remodelling" is where the structure and function of the heart changes in response to stress."It’s our body’s way of adapting to that stress, but ultimately it weakens the heart and can lead to heart failure.," explains Professor Li.Of course, this isn't the first piece of research to examine how light exposure during sleep can cause nighttime awakenings.One 2020 study discovered that those living with heavy light pollution tend to get much less sleep, while a 2021 study found that sleeping in a room with even a small amount of light elevates heart rate throughout the night and lead to disrupted sleep.How I fixed my nighttime light exposure with this genius $5 product (Image credit: Future)Fortunately, the study's accompanying editorial provides some guidance on combating nighttime light exposure, and it's pretty simple."The advice is simple and inexpensive: blackout curtains, warm-coloured bedside lighting, and covering the small standby LEDs on household electronics," writes Professor Thomas Münzel in the commentary.So, the first thing I did was order something that would block the charging light on electronics. I stumbled upon these Light Blocking Stickers, now $4.98 (were $8.99) at Amazon, which promise to dim up to 100% of electronic light.I was sceptical, but to my surprise, this $5 product effectively blocks light from my computer monitor, laptop charger, and extension lead switch. I simply choose a sticker (they come in various shapes and sizes) that can effectively cover the light source, stick it down, and then the problem is fixed.Now, my early morning awakenings have come to a halt — just in time to try out the best sunrise alarm clocks.3 top-rated products to help block out sleep-disrupting light Follow Tom's Guide on Google News and add us as a preferred source to get our up-to-date news, analysis, and reviews in your feeds. 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.