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Blue Light and the Effect on Sleep

Original Editor - Kapil Narale

Top Contributors - Kapil Narale and Angeliki Chorti

What is Blue Light?

Blue light is a form of light that is released approximately between the wavelengths of 400 to 500 nm. [1]

The most common source of blue light is sunlight. Blue light can also be emitted from electronic devices and digital screens, such as televisions, computers, and smartphones, light-emitting diodes (LEDs), and fluorescent lighting. [1]

Some devices are a common source of entertainment and communication and are widely used in daily life. Blue light is emitted with a wavelength that may affect our circadian rhythm. [2] With the advent of digital health in patient and clinician lives, the increased use of technology and blue light may also involve healthcare, and consequently, the urge to learn more about this topic is more prominent.

Benefits of Blue Light

Blue light may have beneficial effects, and some benefits include: [2][3]

  • Better cognitive performance
  • Increase in alertness
  • Lower reaction times
  • Improvement in wellbeing

All the above affect physical and sport performance and thus may promote injury prevention. [2] In addition, exposure to blue light may improve depression symptoms, but efficacy and safety is still unproven. [4]

Negative Effects of Blue Light

Apart from benefits, there are also negative effects that blue light may cause: [2]

  • Less tiredness
  • Poorer sleep quality
  • Reduced sleep duration
  • Decreased sleep efficacy
  • More time to fall asleep

Factors like a decreased sleep quality and duration can have a negative effect on an athlete's physical and cognitive performance, as well as their recovery. According to Tordjman et al (2017), blue light halts the secretion of melatonin, whose main role is to regulate the circadian rhythm. [2]

There are also reports of a decrease in individualised sleepiness with the exposure of blue light. In particular, there was a higher individualised sleepiness level with the use of blue light blocking glasses. [2]

Physics of Blue-Light and the Effect on the Eyes

Light at wavelengths less than 380nm can not be seen by the eyes. [5] However, a wavelength between 300 and 400 nm can transmit through the cornea, and be absorbed by the pupil or iris. Blue light of a wavelength between 415 nm and 455 nm (high energy short-wave) is the most harmful, and associated with eye light damage. When in the direction of the eyes, the high energy blue light transmits through the cornea and lens to the retina, which can cause diseases such as dry eye, cataract, and age-related macular degeneration. Direct transmission of the crystals into the retina would lead to an irreversible photochemical retinal damage. Due to these factors, prolonged exposure to blue light causes acceleration of fatigue in the eyes and nearsightedness. [6]

Blue light can stimulate the brain, diminishing the secretion of melatonin, and improving adrenocortical hormone production, impacting hormonal balance and directly affecting sleep quality. [7] This can decrease the excitability of the parasympathetic nerves and tear secretion, which can help lead to dry eyes. [8] Similarly, sleeping disorders caused by blue light may be influenced by the aging (yellowing) of the lens and decreased transmission of blue light to the retina. [9]

Effect on the Circadian Rhythm

Blue light may influence the circadian rhythm. Blue light activates the secretion of melatonin in the pineal gland. This can increase or decrease cortisol expression depending on the time of the day, and thus can affect the circadian rhythm. [6]

Sleep quality was seen to improve, in older people, after cataract surgery, since the transparent artificial crystal allowed more blue light to reach and transmit through the eye. [6] Alertness, memory, and cognition may also be improved. [2] However, if exposure to blue light is prolonged, especially before sleep when melatonin production is the highest, in addition to retinal damage through the ocular surface, it can also diminish the secretion of melatonin, increase the production of corticosteroids, and damage hormonal secretions, thus harming sleep quality. [6]

Conditions with and without Blue Light

Various studies, as outlined in the systematic review by Silvani et al (2022), consider the effect of blue light on sleep when compared to conditions without blue-light. [2]

It is suggested that any activity performed off a screen, like reading a hard copy book, or an activity using a blue-light filter, has a different effect than using a screen or device which delivers blue-light exposure to the user. Conditions with blue-light blocking glasses or without blue light help with increasing sleep efficiency, and decreasing time to fall asleep. In some cases, the use of devices had no negative effect on sleep characteristics. [2] 

See the Resources section which links to the systematic review describing various studies which consider conditions with and without the use of blue-light.

Blue Light and the Effect on Sleep Quality

As it is commonly known, the exposure to blue light may impact sleep quality. A good indication of sleep quality can be based on a measure of restful and good sleep. [10] Sleep can be considered restful if there is minimal tiredness the next day, sleep efficacy is high, and if time to fall asleep is low. There are many factors that can contribute to sleep health, which include, tiredness, sleep duration, sleep efficacy, and time to fall asleep (sleep latency). Poor sleep quality results in bad sleep. [2]

Silvani et al (2022) noted that thee was a higher sleep quality in a non-blue light condition. One of five studies showed an increase in sleep quality with blue light exposure [11], and one of five studies showed a decrease in sleep quality with blue light exposure [12]. Three studies found that there was no significant change in sleep quality with our without blue light [13][14][15]. These results give a mixed and conflicting impression. [2]

Blue Light and the Effect on Sleep Duration

Three studies included in Silvani et al (2022) showed that there was a decrease in sleep duration with the exposure to blue light [16] [17][18], while one study indicated that there was an increase in sleep duration [11]. Five studies showed that there was no significant difference in sleep duration. [13][15][19][20][21]

Here is a quick video which discusses the effect of blue-light on sleep quality: [22]

Blue Light and the Effect on Sleep Efficacy and Sleep Latency

It is interesting to note that in the systematic review by Silvani et al (2022), two studies reported that there was a higher sleep efficacy without the exposure to blue light [17] [23], while two studies showed that there was no significant difference in sleep efficacy with exposure to blue-light [19] [15]. Only one study found that time to fall asleep was decreased with the non-blue-light condition. Two studies found an increase in time to fall asleep with the blue-light condition. Five studies found no significant difference in time to fall asleep between the blue-light and non-blue-light conditions. [2]

Prevention Strategies

Other than minimising the use of electronic devices before bedtime, certain devices can be used to help minimise the exposure to blue light. Devices such as a blue light glasses or a screen cover can be used. [6]

Blue Light Blocking Glasses

Blue light blocking glasses are used to block blue light, and improve sleep efficiency and sleep latency in various sleep disorder conditions or situations. These can include insomnia, a delayed sleep phase disorder, shift work, jet lag, and non-pathologic sleep improvement. These glasses can help improve sleep with the secretion of dim-light melatonin, with the prevention of light-induced reduction of melatonin release. This happens with the reduced facilitation of intrinsically photosensitive retinal ganglion cells. These are the most susceptible to blue light, and thus a major facilitator for regulation of the circadian rhythm. [24]

A review examined the use of blue light blocking glasses in the evening and its effect on sleep. There was significant evidence that blue-light blocking glasses improved sleep latency in individuals with sleep disorders, jet lag, or those who have varying shift work schedules. [24]

It is seen that blue-light blocking glasses help with inducing sleep, they are great for individuals with insomnia, or a delayed sleep latency. Blue-light blocking glasses can help with blocking blue-light reduced insomnia by enhancing the circadian rhythm. A study found that blue-light blocking glasses improved sleep quality, as well as sleep duration and regularity. Blue light blocking glasses with shades of orange or amber can be effective. It is seen that blue-light blocking glasses can help with achieving a longer sleep duration, fewer sleep interruptions, improved processing speed and short term memory. The use of blue-blocking glasses helps induce enhanced work performance. [24]

However, there can be some adverse effects of using blue-light blocking glasses. It is possible that the glasses can induce physical pain, which can be eliminated with the removal of the glasses. They can also cause a decreased reaction time when carrying out sustained attentional tasks, and decreased visuospatial memory performance. It is also possible that these glasses can induce a lag in the circadian rhythm. [24]

A study compared the use of blue-light blocking glasses for 2 hours before sleeping for 1 week, to the use of clear placebo lenses. The Pittsburgh Insomnia Rating Scale (PIRS) is an objective measure used to outline symptoms, sleep characteristics, and quality of life. The participants with the blue-light blocking glasses had an improved PIRS score, significantly longer duration of sleep, improved overall quality of life, and sleep satisfaction. [24]

Application to Athletes

The positive and negative factors from the exposure to blue light is a consideration to athletes, especially since good sleep hygiene is essential for a strong athletic performance. It is also a possibility that blue light may improve performance, especially since athletes may be in need of sleep as a result of their busy training schedules. With the increased use of electronic devices, the blue-light may impact sleep and lead to tiredness. Tiredness may be a factor impacting physical performance. There are instances where blue-light was seen to decrease tiredness, thus leaving the athletes with an option to decease their tiredness prior to competition. Since blue-light can help with improving physical performance, it can help with reducing injury and help with remaining focused. It is shown that 2 hours of exposure to blue/light can help reduce an athlete's feeling of tiredness. [2]

It is seen that poor sleep quality results in 'bad sleep', thus decreasing an athletes' performance and recovery. These are very important factors for athletes as the performance and recovery will help lead them to success. A recommendation is to reduce blue-light exposure to 3 hours before bedtime, since it was found that athletes' performance decreased with this much blue-light exposure. An improvement in sleep quality can lead to an improvement in reaction time, accuracy, endurance performance, accompanied by a decrease in injury and illness. The athlete would need to make a decision of how they would like to decrease their blue-light exposure. This can also be done with the consultation of their coach. Minimising blue-light exposure for a limited number of hours may be sufficient during period of intense physical activity. [2]

Sleep quality can have an impact on tiredness and one's perception of fatigue, as fatigue seems to be present with poor sleep quality. Thus, decreased level of tiredness would indicate good sleep quality. [2]

It is seen that there may be a reduced sleep duration for athletes due to increased training, and tight schedules. Sleep duration may be even worse with the exposure to blue-light. Sleep duration would have less of an effect on overall fatigue, thus would be less important than sleep quality when considering optimal sleep habits. [2]

Videos

Here are some fun videos which explain the topics mentioned above, talking about blue-light and the effect on sleep.

[25]
[26]

Resources

Table 3 in Silvani et al (2022) describes all the studies that were analysed in this systematic review considering the effect of blue light on sleep. [2]

Table 4 in Silvani et al (2022) (p. 10-12) outline studies considering the effect of blue light on performance, such as cognitive performance, alertness, reaction times, accuracy, daytime dysfunction, heart rate response, and handgrip strength. [2]

Table 5 in Silvani et al (2022) (p. 14) present all the studies considering the effect of blue light on wellbeing, consisting of mood, irritability, arousal, tension, anxiety, and motivation. [2]

References

  1. ↑ 1.0 1.1 Coats JG, Maktabi B, Abou-Dahech MS, Baki G. Blue Light Protection, Part I-Effects of blue light on the skin. J Cosmet Dermatol. 2021 Mar;20(3):714-717.
  2. ↑ 2.00 2.01 2.02 2.03 2.04 2.05 2.06 2.07 2.08 2.09 2.10 2.11 2.12 2.13 2.14 2.15 2.16 2.17 2.18 Silvani M.I, Werder R, Perret C. The influence of blue light on sleep, performance and wellbeing in young adults: A systematic review. Frontiers in Physiology. 2022:13:1-21.
  3. ↑ Alkozei A, Smith R, Pisner DA, Vanuk JR, Berryhill SM, Fridman A, Shane BR, Knight SA, Killgore WD. Exposure to Blue Light Increases Subsequent Functional Activation of the Prefrontal Cortex During Performance of a Working Memory Task. Sleep. 2016 Sep 1;39(9):1671-80.
  4. ↑ Do A, Li VW, Huang S, Michalak EE, Tam EM, Chakrabarty T, Yatham LN, Lam RW. Blue-Light Therapy for Seasonal and Non-Seasonal Depression: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Canadian Journal of Psychiatry. 2022:67(10):745-754.
  5. ↑ Söderberg P, Talebizadeh N, Yu Z, Galichanin K. Does infrared or ultraviolet light damage the lens?. Eye 2016; 30: 241–46.
  6. ↑ 6.0 6.1 6.2 6.3 6.4 Zhao Z-C, Zhou Y, Tan G, Li J. Research progress about the effect and prevention of blue light on eyes. International Journal of Ophthalmology. 2018:11(12):1999-2004.
  7. ↑ Wahl S, Engelhardt M, Schaupp P, Lappe C, Ivanov IV. The inner clock-Blue light sets the human rhythm. J Biophotonics. 2019 Dec;12(12):e201900102.
  8. ↑ Talens-Estarelles C, García-Marqués JV, Cerviño A, García-Lázaro S. Determining the Best Management Strategy for Preventing Short-Term Effects of Digital Display Use on Dry Eyes. Eye Contact Lens. 2022 Oct 1;48(10):416-23.
  9. ↑ Kessel L, Siganos G, Jørgensen T, Larsen M. Sleep disturbances are related to decreased transmission of blue light to the retina caused by lens yellowing. Sleep. 2011:34(9):1215-1219.
  10. ↑ Kohyama J. Which Is More Important for Health: Sleep Quantity or Sleep Quality? Children (Basel). 2021 Jun 24;8(7):542.
  11. ↑ 11.0 11.1 Viola A.U, James L.M, Schlangen L.J.M, Dijk D.J. [https://www.sjweh.fi/article/1268 Blue enriched white light in the workplace improves self-reported alertness, performance and sleep quality.] Scandinavian Journal of Work & Environmental Health. 2008:34:297–306.
  12. ↑ Burkhart K, Phelps J. Amber lenses to block blue light and improve sleep: A randomized trial. Chronobiology International. 2009:26:1602–1612.
  13. ↑ 13.0 13.1 Sander B, Markvart J, Kessel L, Argyraki A, Johnsen K. Can sleep quality and wellbeing be improved by changing the indoor lighting in the homes of healthy, elderly citizens? Chronobiology International. 2015:32:1049–1060.
  14. ↑ Bowler J, Bourke P. Facebook use and sleep quality: Light interacts with socially induced alertness. British Journal of Psychology. 2019:110:519–529.
  15. ↑ 15.0 15.1 15.2 Driller M, Uiga L. The influence of night-time electronic device use on subsequent sleep and propensity to be physically active the following day. Chronobiology International. 2019:36:717–724.
  16. ↑ Münch M, Nowozin C, Regente J, Bes F, De Zeeuw J, Hädel S, Wahnschaffe A, Kunz D. Blue-enriched morning light as a counter-measure to light at the wrong time: Effects on cognition, sleepiness, sleep, and circadian phase. Neuropsychobiology. 2016:74:207–218.
  17. ↑ 17.0 17.1 Yang M, Ma N, Zhu Y, Su Y-C, Chen Q, Hsiao F-C, Ji Y, Yang C-M, Zhou G. The acute effects of intermittent light exposure in the evening on alertness and subsequent sleep architecture. International Journal of Environmental Research. Public Health. 2018:15:524.
  18. ↑ Chindamo S, Buja A, DeBattisti E, Terraneo A, Marini E, Gomez Perez L.J, Marconi L, Baldo V, Chiamenti G, Doria M, Ceschin F, Malorgio E, Tommasi M, Sperotto M, Buzzetti R, Gallimberti L. Sleep and new media usage in toddlers. European Journal of Pediatrics. 2019:178:483–490.
  19. ↑ 19.0 19.1 Chang A-M, Aeschbach D, Duffy J.F, Czeisler C.A. Evening use of light emitting eReaders negatively affects sleep, circadian timing, and next morning alertness. Procedures in National Academic Sciences U.S.A. 2015:112:1232–1237.
  20. ↑ Grønli J, Byrkjedal I.K, Bjorvatn B, Nødtvedt Ø, Hamre B, Pallesen S. Reading from an iPad or from a book in bed: The impact on human sleep. A randomized controlled crossover trial. Sleep. Med. 2016:21:86–92.
  21. ↑ Rångtell F.H, Ekstrand E, Rapp L, Lagermalm A, Liethof L, Búcaro M.O, Lingfors D, Broman J-E, Schiöth H.B, Benedict C. Two hours of evening reading on a self-luminous tablet vs. reading a physical book does not alter sleep after daytime bright light exposure. Sleep Medicine. 2016:23:111–118.
  22. ↑ Essentia Health. Sleep Medicine: How does blue light affect your sleep? - Essentia Health. Available from: https://www.youtube.com/watch?v=uazdAqopYI4&ab_channel=EssentiaHealth [accessed 24 June 2024]
  23. ↑ Ayaki M, Hattori A, Maruyama Y, Nakano M, Yoshimura M, Kitazawa M, Negishi K, Tsubota K. Protective effect of blue light shield eyewear for adults against light pollution from self-luminous devices used at night. Chronobiology. International. 2016:33:134–139.
  24. ↑ 24.0 24.1 24.2 24.3 24.4 Hester L, Dang D, Barker C.J, Heath M, Mesiya S, Tienabeso T, Watson K. Evening wear of blue-blocking glasses for sleep and mood disorders: a systematic review. The Journal of Biological and Medical Rhythm Research. 2021:1-10.
  25. ↑ Sleep Is The Foundation. How BAD is Blue Light for Your Sleep? Available from: https://www.youtube.com/watch?v=ImV7v7OT3Jw&ab_channel=SleepIsTheFoundation (accessed 24/06/2024).
  26. ↑ Doctor Mike. Here's What Blue Light Actually Does To Your Body. Available from: https://www.youtube.com/watch?v=wGnRcX53XBQ&ab_channel=DoctorMike (accessed 24/06/2024).
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