Smartphone Screens and Their Impact on Sleep Quality

A young woman relaxes on a couch, intently focused on her smartphone

At the end of the day are you one of those people that find comfort in scrolling through TikTok's late at night before bed? How about those that binge watch shows on their phones? Did you know that the light emitted from your smartphone is known to cause adverse effects on sleep?

The effect of smartphone light exposure 

In general the sleep cycle is mediated by the different phases of light exposure throughout the day. Exposure of light through your retinal cells in our eyes will send that signal through a pathway called the retinohypothalamic tract which will relay that to the suprachiasmatic nuclei in the hypothalamus (part of the brain). From here the suprachiasmatic nuclei will send the light signal down different pathways; one of which will lead to the pineal gland resulting in the inhibition of melatonin secretion (Brainard et al. 1997). Melatonin is a hormone that is important for advancing or delaying the circadian rhythm; thus inhibition of this hormone due to light can result in the delay of your circadian rhythm, which is crucial for establishing your sleep-wake cycle. 

Adverse effects on sleep 

Smartphone screens emit blue enriched white light; a type of short-wave light considered to be hazardous to the eye and also have adverse effects on your sleep cycle (Wong, Bahmani 2022). In a study that was done on adolescents with varying degrees of smartphone use (people owning a smartphone, new smartphone owners, and non-smartphone owners) it was shown that the smartphone owners reported a significantly higher number of sleep problems (Schweizer et al. 2016). Smartphone blue light exposure coupled with its use during later evening times results in delaying the sleep-wake cycle established by your circadian rhythm. 

In a sleep study that was looking into the effect of smartphone use on sleep in medical students, when looking at the medical students actual screen time their regressional study showed that there was a correlation between increasing screen time and also having a worse Pittsburg sleep quality score (indicating a poorer quality of sleep); for every 1 minute of added screen time their sleep disturbance score increased by 1.234 (Goel et al. 2023). Through further studies it was shown that specifically using your smartphone 2 hours before you sleep while laying in bed had a direct impact on the duration of sleep; there was a mean difference in total sleep for when engaging in 10 minutes of interactive screen time(playing engaging games and commenting on social media posts) there was 9 minutes of sleep lost and 4 minutes of sleep loss for passive screen time(watching videos and engaging in mindless games) (Brosnan et al. 2024). The result of reducing the quality of sleep falls in line with linked disturbances in the sleep cycle that is caused as well from short-wave light exposure. These findings were prevalent in another study that was done on 8 men through analyzing their EEG’s slow wave activity in response to exposure of blue and green light; it was found that exposure to the blue light specifically had reduced the period of rapid eye movement (REM), altered the periods of slow wave activity throughout the sleep cycles, and also reduced the power density of the EEG indicating much shallower sleep (Münch et al. 2006). 

A tranquil moment of rest as a woman peacefully sleeps on a comfortable pillow, embodying serenity and relaxation.

The consequences of sleep disturbances on health

The impacts of sleep disturbances have been associated with an overall negative effect on your health. Sleep is an essential process that is vital to the restoration of various physiological systems; when disturbed your body does not get this time to properly restore and balance many of its components. During the different stages of the sleep cycle there are many essential processes present such as muscle recovery, metabolic regulation, immune system repair, and more. Sleep disruption has been linked to the production of many short and long term issues with short-term effects being increased stress responsivity, emotional distress, mood disorders, performance deficits and long-term being hypertension, dislipidemia, cardiovascular disease, weight related issues, colorectal cancer, and metabolic syndrome (Medic et al. 2017). The list of issues associated with sleep disruption is even longer than was listed.

Conclusion

Smartphone use for as little as 10 minutes about 2 hours before bed can result in affecting the quality of your sleep. Sleep is a critical factor in life and disrupting it can lead to a variety of mental, physical, and physiological problems. So I urge you to ask yourself this one question every night before you go to sleep; is engaging in smartphone use just before bed really worth it? 

Written by Michael Solorio, BS, and edited by Aldrin V. Gomes, Ph.D.

References

Brainard, G., Rollag, M., & Hanifin, J. (1997). Photic regulation of melatonin in humans: Ocular and neural signal transduction. Journal of Biological Rhythms, 12(6), 537–546. https://doi.org/10.1177/074873049701200608

Brosnan, B., Haszard, J. J., Meredith-Jones, K. A., Wickham, S. R., Galland, B. C., & Taylor, R. W. (2024). Screen use at bedtime and sleep duration and quality among youths. JAMA Pediatrics, 178(11), 1147–1154. https://doi.org/10.1001/jamapediatrics.2024.2914

Goel, A., Moinuddin, A., Tiwari, R., Sethi, Y., Suhail, M. K., Mohan, A., Kaka, N., Sarthi, P., Dutt, R., Ahmad, S. F., Attia, S. M., Emran, T. B., Chopra, H., & Greig, N. H. (2023). Effect of smartphone use on sleep in undergraduate medical students: A cross-sectional study. Healthcare, 11(21), 2891. https://doi.org/10.3390/healthcare11212891

Medic, G., Wille, M., & Hemels, M. E. (2017). Short- and long-term health consequences of sleep disruption. Nature and Science of Sleep, 9, 151–161. https://doi.org/10.2147/NSS.S134864

Münch, M., Kobialka, S., Steiner, R., Oelhafen, P., Wirz-Justice, A., & Cajochen, C. (2006). Wavelength-dependent effects of evening light exposure on sleep architecture and sleep EEG power density in men. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 290 (5), R1421–R1428. https://doi.org/10.1152/ajpregu.00478.2005

Schweizer, A., Berchtold, A., & Barrense-Dias, Y. (2017). Adolescents with a smartphone sleep less than their peers. European Journal of Pediatrics, 176, 131–136. https://doi.org/10.1007/s00431-016-2823-6

Wong, N. A., & Bahmani, H. (n.d.). A review of the current state of research on artificial blue light safety as it applies to digital devices. [Preprint] Dopavision GmbH / Max Planck Institute for Biological Cybernetics.