Blue Light Blocking Glasses
Blue Light Blocking Glasses
Our sleep-wake cycle is controlled by our circadian rhythm. The National Institute of General Medical Sciences defines circadian rhythms as physical, mental and behavioural changes that you experience over a 24-hour cycle. Essentially, changes in the day which make up our circadian rhythm affect our sleep-wake cycle.
Specifically, when in the dark, the cells in our eyes send a message to the suprachiasmatic nucleus (SCN) located in the hypothalamus which then tells the pineal gland to produce the hormone melatonin. Cut short, Melatonin makes us feel sleepy. On the flip side, when the cells in our eyes detect light, they send a message to the SCN to block the production of melatonin so that we can wake up more easily.
Currently, we have a lot of blue light before going to bed. Our exposure to blue light takes many forms such as watching TV, phone scrolling and reading e-readers. Blue light before bed signals to the brain that it is not sleeping time yet (cells do not detect darkness so they do not communicate to the SCN and the SCN does not tell the pineal gland to release melatonin) making us stay awake.
People have taken to wearing blue light glasses to block blue light exposure. This article looks to discuss what the research suggests about the effectiveness of blue light blocking glasses.
Sleep Duration and Quality
One study carried out in 2021 conducted a 1-week intervention where 10 participants wore blue light glasses and 10 wore clear glasses (used as a control). Participants wore the glasses for 7 consecutive days from 6pm until bedtime. They found that blue light glasses positively impacted subjective sleep onset and awakenings in the night (people thought they were sleeping longer and woke up less) but did not improve objective measures of sleep time or quality in healthy adults (Bigalke et al., 2021).
Another study also had 20 participants (10 wore blue light blocking glasses and 10 wore UV blocking glasses) 3 hours before bed for 2 weeks. As a measure of sleep quality and duration participants completed sleep diaries. At the end of the study, the participants who wore the blue light blocking glasses reported significant improvement in sleep quality and mood compared to the participants who wore the UV blocking glasses (Kimberly & James R., 2009).
Impact on Melatonin and Deep Sleep
The research into blue light blocking glasses highlights their impact on melatonin production. One study exposed 14 people at night to a 60-minute bright light pulse whilst wearing blue light blocking glasses or grey lens glasses (not blocking). They found a small increase in melatonin in the blue light blocking lens group (higher levels of the sleepy hormone) and a large reduction of melatonin (46%) in those who wore grey lens glasses (lower levels of the sleepy hormone). They concluded that blue light blocking glasses prevent the blocking of melatonin from blue light (Sasseville et al., 2006). Furthermore, blue light blocking glasses have been shown to significantly reduce LED-induced melatonin suppression (blocking of melatonin from LED) in the evening and decreased attention and alertness before bedtime. (van der Lely et al., 2015).
Another study looked at the sleep quality, ratio of deep sleep and body movements during sleep. They found that in participants who were exposed to blue light deep sleep was significantly decreased compared to those who wore blue light blocking glasses. They also found that blue light blocking glasses had no effect on sleep duration or body movements (Ishizawa et al., 2021).
Eye Strain
Blue light blocking glasses and their impact on eye strain has been investigated. One study had 23 healthy young adults who undertook two reading tasks on a computer screen and measured its impact with or without blue light blocking filters on eye strain. They concluded that there was no evidence to suggest that using blue light blocking filters affected symptoms of eye strain (Vera et al., 2023). This conclusion was also supported by a different study in which participants engaged with 20 minutes of reading from a tablet computer. They also concluded that there was very little evidence to support the use of blue light blocking filters as a clinical treatment for digital eye strain (Rosenfield et al., 2020).
Blue Light Blocking Glasses and Other Disorders
Blue light blocking glasses have been found to be effective intervention for different disorders. In one study individuals with Parkinson’s Disease wore blue light blocking glasses daily for at least one week (Smilowska et al., 2019). The results showed that 84% of participants had an overall positive attitude towards the glasses and 74% of participants reported a subjective improvement in nighttime sleep. Furthermore, only 1 out of the 31 said that they would not carry on wearing the glasses.
A systematic review was carried out of 12 studies looking into the effects of wearing light blocking glasses before sleep. They summarised that the findings are mixed. However, the research did show that light blocking glasses are more effective for those with insomnia, bipolar, ADHD and delayed sleep phase syndrome (Shechter et al., 2020).
Summary
The research seems to suggest that blue light blocking glasses do not increase sleep duration or help alleviate symptoms of eye strain. The findings were mixed on sleep quality, which needs further investigation. However, the blue light blocking glasses seem to be an effective intervention in reducing symptoms of certain disorders in which case they might be worth a try.
The most interesting findings from the research is how blue light blocking glasses impact melatonin levels and subjectiveness of sleep. The glasses have a positive impact on melatonin which increases your readiness for sleep. This may suggest that sleep duration is being influenced by something else. The glasses will certainly make you feel as though you are sleeping better and for longer so if that’s your goal, they may be worth the purchase.
References
Bigalke, J. A., Greenlund, I. M., Nicevski, J. R., & Carter, J. R. (2021). Effect of evening blue light blocking glasses on subjective and objective sleep in healthy adults: A randomized control trial. Sleep Health, 7(4), 485–490. https://doi.org/10.1016/j.sleh.2021.02.004
Ishizawa, M., Uchiumi, T., Takahata, M., Yamaki, M., & Sato, T. (2021). Effects of pre-bedtime blue-light exposure on ratio of deep sleep in healthy young men. Sleep Medicine, 84, 303–307. https://doi.org/10.1016/j.sleep.2021.05.046
Kimberly, B., & James R., P. (2009). Amber Lenses to Block Blue Light and Improve Sleep: A Randomized Trial. Chronobiology International, 26(8), 1602–1612. https://doi.org/10.3109/07420520903523719
Rosenfield, M., Li, R. T., & Kirsch, N. T. (2020). A double-blind test of blue-blocking filters on symptoms of digital eye strain. Work, 65(2), 343–348. https://doi.org/10.3233/WOR-203086
Sasseville, A., Paquet, N., Sévigny, J., & Hébert, M. (2006). Blue blocker glasses impede the capacity of bright light to suppress melatonin production. Journal of Pineal Research, 41(1), 73–78. https://doi.org/10.1111/j.1600-079X.2006.00332.x
Shechter, A., Quispe, K. A., Mizhquiri Barbecho, J. S., Slater, C., & Falzon, L. (2020). Interventions to reduce short-wavelength (“blue”) light exposure at night and their effects on sleep: A systematic review and meta-analysis. SLEEP Advances, 1(1), zpaa002. https://doi.org/10.1093/sleepadvances/zpaa002
Smilowska, K., van Wamelen, D. J., Schoutens, A. M. C., Meinders, M. J., & Bloem, B. R. (2019). Blue Light Therapy Glasses in Parkinson’s Disease: Patients’ Experience. Parkinson’s Disease, 2019(1), 1906271. https://doi.org/10.1155/2019/1906271
van der Lely, S., Frey, S., Garbazza, C., Wirz-Justice, A., Jenni, O. G., Steiner, R., Wolf, S., Cajochen, C., Bromundt, V., & Schmidt, C. (2015). Blue Blocker Glasses as a Countermeasure for Alerting Effects of Evening Light-Emitting Diode Screen Exposure in Male Teenagers. Journal of Adolescent Health, 56(1), 113–119. https://doi.org/10.1016/j.jadohealth.2014.08.002
Vera, J., Redondo, B., Ortega-Sanchez, A., Molina-Molina, A., Molina, R., Rosenfield, M., & Jiménez, R. (2023). Blue-blocking filters do not alleviate signs and symptoms of digital eye strain. Clinical and Experimental Optometry, 106(1), 85–90. https://doi.org/10.1080/08164622.2021.2018914