Put The Phone Away, The Light Is Killing Your Sleep!

Written by Dr. Pulyk Nataliya Omelanivna on Fri, 11 November 2022

Key Highlights

  • Most living organisms, including humans, have evolved to respond to light and darkness. Artificial light disrupts that evolutionary response and disrupts sleep.
  • Artificial light makes us stay up till late night and adversely affects the production of melatonin, the hormone that helps us fall asleep and brings down the body temperature.
  • Of all the artificial lighting that we're exposed to, blue light is the worst one for sleep, and most of our device screens emit light in the blue wavelength.
  • Blue light is natural, and it's energizing during the day, but for exactly that reason, it's not so beneficial when we have to sleep.
  • To get enough sleep, you need to stay away from all screens for at least 60 minute before bedtime.
  • Darken your bedroom before going to sleep at night, and take in as much sunlight as possible during the day.

The body of research into the connection between blue light and sleep is growing, but judging by the number of people who still scroll up and down their phone screens lying in bed, public awareness on how blue light affects sleep hasn't grown at the same pace.

Why blue light before bed can keep you awake

Sleep deprivation being a global phenomenon nowadays, it's vital to understand why blue light before bed can keep you awake, so that you can remedy the situation and get the quality of sleep you need. 

Lack of sleepA good night's sleep is essential for mental alertness and physical wellbeing; on the flipside of the coin, prolonged sleep deprivation can have a destructive impact on health.

People go to sleep at night because they've accumulated fatigue during the day. They get up in the morning rested and can function throughout the day because they've slept well the night before. This work-rest-work cycle is disrupted when someone doesn't sleep well and, therefore, wakes up today with the residual fatigue of yesterday.

If this continues for a long time, the lack of sleep begins to increase that person's risk of weight gain, high blood pressure, and diabetes; affects professional performance; may affect personal relationships; and could even result in a car accident if the person drives in a sleep-deprived state.

"Globally, insufficient sleep is prevalent across various age groups, considered to be a public health epidemic that is often unrecognized, under-reported, and that has rather high economic costs," says the abstract of a 2019 research paper titled 'The Global Problem of Insufficient Sleep and Its Serious Public Health Implications'.

That's why, it's important to establish good sleep hygiene. In fact, in any sleep disorder, it's useful to review your waking and sleeping behaviors. Good sleep hygiene helps us fall asleep quickly and get restorative sleep, waking up at night as little as possible.

How does blue light affect sleep?

Blue light affect sleepLight pollution is one of the major drawbacks of modern life, and blue light from devices such as smartphones, laptops, large display screens, LED light bulbs, LED television sets, digital readers, handheld gaming systems, etc is one of the main causative factors.

'Blue light' is so called because of its blue wavelength, blue being one of the seven colors of the VIBGYOR spectrum that forms visible light. "There couldn't be anything more ordinary than blue light. It's the reason the sky looks blue — because it bounces off the molecules in the Earth's atmosphere more readily than the rest of the visible light spectrum," explains an article in BBC Science Focus Magazine.

Therefore, there's nothing unnatural about blue light itself; what's unnatural is that blue light keeps hitting our eyes till late night, long past sunset, because of general light pollution and nonstop device use. That changes our circadian rhythm.

According to the National Sleep Foundation, United States, when the body is exposed only to the natural light of the sun, the hypothalamus area of the brain sets its sleep patterns according to daylight and darkness. Light is detected by the retina, which sends signals to the hypothalamus. 

As it starts getting dark outside, the hypothalamus signals to the body to start creating sleep hormones like melatonin and to drop the person's body temperature to prepare for sleep. The next morning, when daylight is sensed, the body is told to warm up and to produce hormones like cortisol that wake the body up.

Melatonin at work

Researchers have long known that light is the most powerful cue for resetting the time of the circadian clock, the "biochemical oscillator" inside the body. 

They also know that melatonin is present at low levels during the day, begins being released a few hours before bedtime and peaks in the middle of the night.

functions of melatoninMelatonin is known to:

  • Improve the function of the immune system
  • Normalize blood pressure
  • Improve thyroid function
  • Improve insulin sensitivity
  • Reduce the proliferation of cancer cells
  • Enhance DNA protection
  • Decrease risk of Alzheimer's 

Past studies have shown that light suppresses melatonin — light in the early evening causes a circadian delay, or resets the clock to a later schedule; and light in the early morning causes a circadian advancement, or resets the clock to an earlier schedule.

In the 1990s, more than 700 experiments conducted over seven years to measure how different wavelengths of light regulate acute melatonin production resulted in the finding that humans display peak sensitivity to light in the blue wavelength region of the spectrum.

Recent studies have also shown that short-wavelength (blue) light has a greater effect on phase shifting the circadian clock and on melatonin suppression. That's why, people who don't turn off their devices well before going to bed, stay up longer and experience even more circadian delay and shorter sleep times.

A 2015 article by Jessica Schmerler in the Scientific American Mind that quotes Thomas Jefferson University neuroscientist George Brainard (among the first researchers to investigate how different wavelengths of light affect the release of melatonin) and Harvard University neuroscientist Anne-Marie Chang (who recently discovered that the effects of light-emitting devices on circadian systems extend beyond evening and into the following morning), says: "For those who just cannot turn off digital devices, you can dim the brightness of your devices or you can make use of programs that filter out short-wavelength light in the evening."

The neuroscientists believe that the best course of action would be to simply avoid your devices before going to sleep.

Heard of light pollution?

Any adverse effect from artificial light is referred to as "light pollution". It affects not just humans, but animals, too.

Studies show that exposure to room light during usual hours of sleep suppresses melatonin levels by more than 50%. Humans and most other organisms have evolved to adjust to predictable light and dark phases. Once artificial light became the lifestyle norm, it effectively changed our sleep cycle for the worse. 

  • Findings presented at the American Academy of Neurology's annual meeting in Vancouver, Canada, suggest that people who live in neighborhoods that are lit up at night with neon signs and many streetlights are more likely to report sleep problems.
  • In an urban area, we all tend to shorten our sleep a lot more, because it's a busy, vibrant environment, so we're up till late night, and maybe we're exposed to bright light inside our homes — all of that leaves us with a huge sleep debt. 

Since sleep is an essential part of the day, it's absolutely vital to limit the exposure to light in general before bedtime and to blue light in particular.

  • A 2019 study published in the Journal of Biophonetics says that while exposure to the blue wavelength of light is important for an organism's wellbeing, alertness, and cognitive performance during the day, chronic exposure to low‐intensity blue light directly before bedtime may have serious implications on sleep quality, circadian phase, and sleep cycle durations.

Blue light prevents the body from activating the natural mechanism that reduces body temperature as we fall asleep. That leads the body to maintain its normal temperature throughout the night, thereby disturbing our sleep.

  • Another study from the University of Houston College of Optometry says that blue light boosts alertness, which we don't want at night. This artificial light activates photoreceptors called intrinsically photosensitive retinal ganglion cells (ipRGCs), which suppress melatonin. These cells communicate directly with the brain. The cells send signals to the suprachiasmatic nucleus (SCN), the so-called master clock of the brain, which impacts sleep due to blue light.

How to end light pollution at home?

reduce blue light before bedtimeOur genes expect us to sleep in total darkness. Getting rid of the light pollution in your bedroom is the key to getting the most peaceful and rejuvenating sleep possible. 

Because you can't control the world outside, you need to take full control of the world in your home.

Here are a few power tips:

  • Get blackout curtains.
  • Banish electronic devices and the TV from the bedroom.
  • Turn off your phone before sleep time.
  • Avoid screens at least 60 minutes before bedtime.
  • Dim or darken your bedroom before bedtime.

Make use of natural light

  • Use as much natural light as possible to let your body reset its clock. 
  • Keep your curtains open throughout the day, and go for walks while the sun is out. 
  • Sunlight also helps to regulate your body's hormones, thus making it a lot easier for your body to secrete the chemicals necessary for quality sleep.

Does light therapy help with sleep?

Some types of light help you sleep better. A 2018 report from the American Academy of Sleep Medicine says that a systematic light exposure intervention with a mixed group of fatigued cancer survivors was significantly more effective than dim light exposure in improving sleep efficiency.

According to researchers from the Department of Psychology, Flinders University, Australia, studies over the past 20 years have shown that appropriately timed bright light can change the timing of the circadian rhythm. 

For example, morning bright light will change the phase of the circadian rhythm to an earlier time. Therefore, this could be a suitable light therapy for individuals with sleep onset insomnia who have difficulty falling asleep until quite late (e.g. midnight or later). With an earlier timed circadian rhythm, they may be able to fall asleep and wake earlier following a regime of morning light therapy.

Bright light administered in the evening has been shown to delay the circadian rhythm. Therefore, using a regime of evening bright light therapy, individuals experiencing early morning awakening insomnia may be able to delay their sleep/wake cycle, resulting in a later wake-up time. Overall total sleep time would increase and daytime functioning would improve.


According to Stanford Health Care, this technique, also called phototherapy, uses appropriately timed exposure to light to help delay the patients' biological clock. The source of light could be artificial, such as a full-spectrum lamp at 10,000 lux or portable visor at lower light intensity or, when reliably available at the right time, natural outdoor light.

Longer properly timed light exposure is better, with recommended exposure duration of 30-90 minutes. The ideal timing of the light exposure depends on the best approximation available of the person's circadian clock.

Sleep schedule maintenance

The sleep specialist works with the patient to decide on the timing and help the patient slowly shift the sleep period to an earlier time. After the desired sleep schedule is attained, patients should maintain a fixed rise time (even on weekends and vacations) and ideally continue to use morning light exposure on most mornings, though the duration of light exposure can be shorter.

Specialists often recommend using dim lights in the evening in conjunction with bright light exposure in the morning during the advancement of the sleep schedule. For maintenance, some patients continue the treatment indefinitely, while some reduce their daily treatment to 15 minutes. Others may use the lamp a few days a week or even every other or third week. The degree of success is different for each patient.

Types of bright light therapy 

The American Academy of Sleep Medicine Foundation lists the different types of bright light therapy to alleviate sleep issues:

Light box: During a treatment session, you must keep within a certain distance of the box, usually 18 to 24 inches. You don't have to look directly into the light. Instead, you simply face in the direction of the box.

Desk lamps: This serves the same purpose as a light box, but it's made to look like a normal lamp. It works better in an office setting.

Light visor: This is a light source that's worn on your head and hangs over your eyes. The strength of visor lights varies from 3,000 to 10,000 lux.

Dawn simulator: These lights gradually make a dark room brighter over a set amount of time. This is meant to mimic the sunrise.

What to do if you can't fall asleep?

When you get less sleep, you're more prone to distraction. And when you're distracted, you start checking your social networks, and that means… even less sleep. It's a vicious cycle.

You need to switch off your screen at least 60 minutes before bedtime. But that's not easy, so here are some tips to help you:

  • Create off-screen schedules: Chalk out a schedule of light activities and small chores that you must complete every night before bedtime. These will automatically keep you away from your TV, laptop, and phone.
  • Read something that's not on a screen: Paper books still exist! Try them for at least 30 minutes every night instead of your favorite websites and social media.
  • Make dinner a family time: Don't eat dinner in front of the TV and don't text during meals. Sit down for dinner as a family every night; have real conversations. Eat at the dinner table even if you live alone.
  • Spend time outdoors regularly: Often, it's boredom that drives us to the screens. Go for a jog, take kids for ice cream, take your dog for a walk more often, do some window-shopping, shop physically instead of online… it will keep you away from the screens without boredom. 
  • Try some meditation: Give yourself some real quiet time that'll also help you connect with your inner self much better. 


Light is the strongest environmental time cue that impacts the body's internal 24-hour clock. Light pollution affects production of the hormone melatonin, which guides the body towards sleep. All bright lights close to bedtime can damage the prospects of good sleep, but the blue light from electronic screens and LED lights has a particularly severe impact. 

To get the sleep you need, rethink your use of electronic devices and your exposure to light. Like all lifestyle issues, sleep deprivation, too, can be remedied with behavioral changes.


Dr. Pulyk Nataliya Omelanivna

Dr. Pulyk Nataliya Omelanivna is an Internal Medical Expert who is based out of Ukraine. With a special interest in internal medicine Dr Pulyk graduated from the Ternopil National Medical Academy in Ukraine, in the year 2001. Between the years 2002-2009, Dr Pulyk worked as an emergency physician. Her years of work as an emergency physician gave her immense exposure to a range of patients and an opportunity to learn on the job, and gather extensive experience.

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  1. NIH: The Global Problem of Insufficient Sleep and Its Serious Public Health Implications
  2. ScienceDaily: Artificial light from digital devices lessens sleep quality
  3. J Biophotonics. 2019 Dec; 12(12): e201900102. Published online 2019 Sep 2. doi: 10.1002/jbio.201900102. PMCID: PMC7065627. PMID: 31433569
  4. NIH: The inner clock—Blue light sets the human rhythm  
  5. ScienceDaily: Lights out: The neural relationship between light and sleep
  6. Sleep Foundation: Light Therapy for Insomnia Sufferers 
  7. Stanfordhealthcare: Bright Light Therapy 
  8. Parelman School of Medicine : The Use of Bright Light in the Treatment of Insomnia 
  9. Sleepeducation: Bright Light Therapy