Light shapes our daily rhythms. Throughout most of human history, the rising and setting of the sun was the primary light cue guiding wakefulness and sleep. Today we live in a world bathed in artificial light from phones, tablets and televisions. Blue‑wavelength light, with a peak around 450–480 nanometres, is particularly effective at stimulating photoreceptors in the eye that signal the brain to stay alert sleepfoundation.org. Using screens late at night suppresses melatonin – the hormone that makes us drowsy – and can shift the body’s internal clock sleepfoundation.org. To counteract this effect, companies have popularised glasses that filter out blue light. Their marketing promises better sleep and deeper rapid‑eye‑movement (REM) sleep. But do blue‑light‑blocking glasses live up to the hype?
This article explores the science behind blue light, circadian rhythms and REM sleep. It reviews the evidence for and against blue‑light‑blocking lenses, highlights recent studies and explains why a well‑designed “sleep experiment” is needed in 2025. We also offer practical tips for protecting your sleep without investing in expensive eyewear.
Blue Light and Your Body Clock
How blue light influences sleep
Visible light spans wavelengths from roughly 400 to 700 nanometres. Blue light sits at the high‑energy end of this spectrum. In the daytime, blue‑enriched light synchronises our internal 24‑hour “circadian” clock and keeps us alert health.harvard.edu. Specialised photoreceptors in the retina contain the pigment melanopsin, which is most sensitive to blue‑green wavelengths around 480 nm. When stimulated, these cells send signals to the brain’s suprachiasmatic nucleus, delaying the release of melatonin and promoting wakefulness.
At night this effect becomes problematic. Exposure to blue light in the hours before bedtime suppresses melatonin and tricks the brain into thinking it is still daytime, causing delayed sleep onset and reduced sleepiness sleepfoundation.org. Chronic circadian misalignment is linked to metabolic disorders and mental health issues such as depression sleepfoundation.org. Common sources of artificial blue light include fluorescent and LED lamps and the screens of smartphones, televisions and computers sleepfoundation.org.
Evidence that blue light delays sleep and reduces REM
Several experiments show how evening blue‑light exposure affects sleep architecture. In a controlled study at Harvard, 16 healthy adults were exposed to blue light or green light for 6.5 hours. Blue light suppressed melatonin for more than twice as long as green light and shifted circadian rhythms by about two hours nature.com. The participants also reported greater alertness under blue light.
Another landmark study compared reading a light‑emitting tablet with reading a printed book. Participants reading from the tablet before bed took almost ten minutes longer to fall asleep, experienced a marked phase delay in melatonin onset and had reduced REM sleep pmc.ncbi.nlm.nih.gov. They also felt less alert the next morning. These findings suggest that blue light from electronic devices can measurably reduce REM, the stage of sleep associated with dreaming, emotional processing and memory consolidation.
What Is REM Sleep?
Sleep is not a uniform state. Each night we cycle through non‑REM stages (N1, N2, N3) and REM sleep. A full cycle lasts about 90–120 minutes and repeats four to six times per night sleepfoundation.org. REM sleep is the final stage in each cycle and has unique characteristics: brain‑wave activity resembles wakefulness, most skeletal muscles are temporarily paralysed, breathing and heart rate become irregular, and the eyes dart rapidly under the eyelids.
REM sleep is vital for several reasons. It helps the brain remove metabolic waste and prepare for clear thinking the next day. It is the stage when most vivid dreams occur and may support emotional processing. REM sleep also strengthens connections between brain regions, aiding memory consolidation and working memory. Most adults need roughly two hours of REM per night, but the amount can vary. When people do not get enough REM, they may experience difficulties concentrating, forgetfulness, moodiness and increased risk of accidents.
The Science of Blue‑Light‑Blocking Glasses
How do these glasses work?
Blue‑light‑blocking glasses use tinted lenses or special coatings to filter out wavelengths below about 500 nm. By removing the portion of the spectrum that most strongly influences melanopsin-containing photoreceptors, the glasses aim to reduce the melatonin‑suppressing effect of evening light. Manufacturers sell lenses in amber, orange or yellow tints and often market them as a simple fix for insomnia, eye strain and digital fatigue.
Early studies: promising but limited
The first controlled trial of amber lenses for sleep appeared in 2009. Twenty volunteers with sleep complaints were randomly assigned to wear amber glasses or clear lenses for three hours before bedtime. Those wearing the amber lenses reported better sleep quality and improved mood compared with the control group. However, the study was small, lasted only one week and did not measure objective sleep stages.
Researchers in Switzerland later tested blue‑blocking glasses in teenage males who used LED screens at night. Wearing blue‑blocking glasses for two weeks increased evening melatonin and reduced alertness compared with clear lenses, but electroencephalogram (EEG) recordings showed no difference in REM or other sleep stages nature.com. In other words, the glasses restored melatonin secretion but did not change the proportion of REM sleep.
Randomised trial in people with insomnia
A more rigorous trial published in 2018 involved fourteen adults with insomnia symptoms. Participants wore amber lenses or clear placebo lenses for two hours before bedtime over a seven‑night period in a randomised crossover design. The amber lenses significantly improved scores on the Pittsburgh Insomnia Rating Scale, increased self‑reported total sleep time and quality, and resulted in longer total sleep time measured by wrist actigraphy pmc.ncbi.nlm.nih.gov. The authors concluded that amber lenses are a safe, low‑cost intervention for insomnia. Notably, this study did not measure REM sleep directly, but improvements in total sleep time suggest a possible indirect benefit.
Evidence that blue‑light blockers do not boost REM sleep
Despite early optimism, newer research raises doubts about the ability of blue‑light‑filtering lenses to meaningfully alter sleep stages. A large systematic review by the Cochrane Collaboration assessed 17 randomised controlled trials with 619 participants and concluded that there is limited information about the effects of blue‑light‑filtering lenses on sleep measures cochrane.org. The review emphasised that existing evidence is inconclusive and that harmful effects such as headaches and mood changes were reported in some studies. In other words, we still do not know whether these glasses meaningfully improve REM or overall sleep quality.
Harvard sleep expert Dr. Steven Lockley notes that most commercially available blue‑light‑blocking glasses are not standardised, meaning consumers have no way of knowing which wavelengths are being blocked health.harvard.edu. A recent systematic review mentioned by Harvard suggested possible benefits for people with insomnia, but Dr. Lockley cautioned that the timing, duration and nature of nighttime light exposure were unclear. The Harvard Health blog therefore recommends avoiding screens after dusk and using software that reduces blue light rather than relying solely on glasses.
The Sleep Foundation notes that while specialty glasses can reduce melatonin suppression, simply turning off or dimming blue‑emitting light sources in the evening is more effective. They advise setting an alarm to remind you to turn off electronics two or three hours before bed and using night‑mode settings or red‑orange lighting when reading. This aligns with evidence showing that behavioural changes, not just filters, are necessary to protect circadian rhythms.
Mixed results from recent reviews
Health news site Verywell Health summarised a 2023 review of studies and concluded that while some trials found improvements in sleep quality with blue‑light‑blocking glasses, others found no significant effect verywellhealth.com. The article warns that the lenses are unlikely to harm eye health because the amount of blue light emitted from screens is low, but they may not provide consistent benefits. It suggests using device night settings, avoiding screens before bed and practicing good sleep hygiene instead.
Emerging Research: The 2025 Sleep Experiment
Ultrahuman’s pilot study
Interest in blue‑light‑blocking glasses continues to grow as wearable technology companies promote them as sleep aids. In March 2025 the health‑tech firm Ultrahuman released a white paper describing a pilot study involving 13 participants. Eight volunteers wore blue‑light‑blocking glasses from dusk until bedtime for four weeks while all participants wore a ring device that tracked sleep quality, heart rate and stress blog.ultrahuman.com. The researchers reported that participants who wore the glasses maintained their sleep quality even after discontinuing use, and their resting heart rate remained stable. Those not wearing the glasses experienced fluctuating sleep scores and heart rate.
While intriguing, this study had major limitations. It included only a small number of participants and was not peer‑reviewed. The report did not specify whether REM sleep was measured directly. Ultrahuman acknowledges that more research on larger populations is needed. Nonetheless, it hints at the growing interest in sleep experiments that extend beyond standard laboratory settings.
Designing a proper sleep experiment
For a definitive answer on whether blue‑light blockers boost REM, scientists must design a rigorous randomised controlled trial. Key features of such a study would include:
- Adequate sample size: A large, diverse group of participants, including people with insomnia and healthy sleepers.
- Objective measurements: Polysomnography (sleep lab recordings) or validated wearable technology to track sleep stages, including REM, rather than relying solely on self‑reported sleep diaries.
- Standardised lenses: Glasses should be tested for their spectral filtering properties to ensure that the same wavelengths are blocked across participants health.harvard.edu.
- Controlled light exposure: Participants should adhere to consistent lighting conditions during the trial. Ideally, the study would include a week of baseline measurements followed by intervention weeks with amber lenses and clear control lenses in a crossover design, as in the 2018 trial.
- Longer follow‑up: The trial should run for several weeks and include follow‑up after lens use is discontinued to examine any persistent effects, similar to the Ultrahuman pilot.
By focusing on REM sleep outcomes – such as total REM duration and REM latency – the 2025 Sleep Experiment could finally answer whether blocking blue light truly enhances this vital stage of sleep.
Do Blue‑Light Blockers Boost REM? A Balanced Verdict
The current evidence suggests that blue‑light‑blocking glasses may improve subjective sleep quality in certain circumstances, particularly for people with insomnia. Amber lenses can reduce melatonin suppression and may help users fall asleep earlier or sleep longer. However, there is little direct evidence that these lenses increase REM sleep. One small Swiss study showed that blue‑blocking glasses raised evening melatonin but did not change REM or other sleep stages, and the Cochrane review concluded that effects on sleep measures are unclear. The 2015 eReader study demonstrated that avoiding blue‑rich screens altogether may be more important; tablet reading delayed sleep, reduced REM and decreased next‑morning alertness.
In summary, while blue‑light‑blocking glasses might be a helpful tool for some, they are not a guaranteed solution for boosting REM. The most reliable way to protect your REM sleep is to limit exposure to bright screens and blue‑rich lighting in the evening, maintain a consistent sleep schedule and practice good sleep hygiene.
Practical Tips to Improve REM Sleep
Even without specialised glasses, you can take simple steps to support healthy REM sleep and overall sleep quality:
- Reduce evening light exposure. Dim or turn off LED and fluorescent lights after sunset and avoid screens at least two hours before bed. If you must use screens, enable “night mode” or install apps that shift the color temperature to warmer hues.
- Use red or orange lighting at night. The Sleep Foundation suggests using lamps that emit red or orange light when reading in bed. These wavelengths have minimal impact on melatonin.
- Set a regular sleep schedule. Go to bed and wake up at the same times each day, even on weekends. Consistency helps regulate your circadian clock and ensures enough REM time.
- Create a sleep-friendly environment. Keep your bedroom dark, quiet and cool. Use blackout curtains or an eye mask if necessary.
- Get daytime light exposure. Spending time outside in natural daylight helps synchronise your body clock. Morning light is particularly effective at anchoring your circadian rhythm.
- Limit caffeine and alcohol. Both substances can reduce REM sleep. Avoid caffeine after midday and moderate alcohol intake.
- Exercise regularly but not late at night. Physical activity promotes deeper sleep, but vigorous workouts just before bed can be stimulating. Aim to exercise earlier in the day.
- Manage stress. Meditation, relaxation techniques and mindfulness can improve sleep quality and may support REM sleep by reducing arousal before bedtime.
Conclusion
Blue‑light‑blocking glasses are an appealing, high‑tech solution for our screen‑saturated lives. They filter out the wavelengths most likely to suppress melatonin, and small studies show they can improve subjective sleep quality in people with insomnia. However, there is scant evidence that they significantly boost REM sleep. Blue light from devices clearly delays sleep onset and reduces REM, but simply filtering part of the spectrum may not be enough to undo these effects. A well‑designed 2025 Sleep Experiment using objective sleep measurements could provide more definitive answers.
In the meantime, the best strategy for preserving REM sleep is to respect your circadian rhythm: minimise evening exposure to artificial light, establish a consistent bedtime routine, and allow yourself the full seven to nine hours of rest your body needs. Blue‑light‑blocking glasses can be a supportive tool, but they should complement, not replace, broader lifestyle changes.
