Welcome to Focus on Fatigue,
How many of us, when we get into bed at night, turn off the light and go straight to sleep? Probably not that many. Instead, we often take out our phone or tablet to check email, surf the internet, play a game or read a book. An hour or two later we plug our electronic device in to charge on the bedside table and lie down ready to go to sleep. But will we go to sleep as quickly, or sleep as soundly, after staring at a screen right before closing our eyes? That’s the question we’ll be attempting to answer in this month’s Focus on Fatigue.
The FRMS Team
InterDynamics Pty Ltd
320 Adelaide Street Brisbane Qld 4000
Tel +61 2 8404 0400 Ext 23
Views expressed in articles and links provided are those of the individual authors, and do not necessarily represent the views of InterDynamics (except where directly attributed).
The Blue Light Blues
It has long been known that our bodies use light to help keep our circadian rhythm in check. The setting of the sun triggers a host of changes in our brains that make us feel sleepy. Then, as dawn lightens the sky, this process is reversed and our brains encourage us to wake up. Then the electric lightbulb was invented. Suddenly, we were bathed in light at all hours of the day and night. We managed to adapt to these changes, with most people still able to achieve adequate sleep each night, even if they did keep the lights on until well after dark. However, the introduction of electronic devices, such as phones and tablets, have thrown a whole new spanner in the works.
Why are electronic devices such a problem for sleep?
Most of the light that illuminates our days and nights is white light. The light produced by the sun is made up of all the colours on the spectrum mixed together, which makes white light. Also, while the lightbulbs we use in our standard light fittings can come in a whole range of colours (such as extra warm or cool), they are essentially all white light.
The light emitted by our electronic devices is different – it’s blue light. We might not be able to perceive the difference, but that doesn’t stop our brains from reacting differently. Blue-enriched light has been found to reset the timing of the circadian rhythm, suppress melatonin (the hormone that makes us feel sleepy), and elevate brain activation. All of which, reduce the likelihood of us falling asleep.
During the day, there are benefits to the presence of blue-enriched light in our lives. Exposure to blue-enriched light can improve subjective measures of alertness, positive mood, performance, and concentration. It can also reduce daytime sleepiness.
At night, however, exposure to blue-enriched light can lead to a number of negative consequences, such as:
- reduced evening sleepiness,
- increased sleep latency (it takes longer to fall asleep),
- reduced slow-wave activity during NREM sleep,
- reduced REM sleep, and
- reduced next morning alertness (even when sleep duration is the same).
Some of the research also suggests that blue-enriched light exposure could lead to an increased risk of delayed sleep-phase disorder, sleep onset insomnia, and chronic sleep deficiency.
What can we do about it?
Several strategies have been developed to help reduce the effects of blue-enriched light on sleep, such as:
- Don’t use any electronic devices without an hour of bedtime.
- Those who enjoy reading a book before sleep should read a paper book or use an e-reader that is not backlit, such as some Kindles (if you don’t need your bedside light on to read it, it’s backlit).
- It is possible to purchase glasses with orange-tinted lenses which reduce exposure to blue-enriched light. These glasses are mass produced, easily available and inexpensive.
- Many devices have a night mode, which reduces the use of blue-enriched light.
- A variety of software is available that can apply a mask or filter to the device itself to reduce blue-enriched light emissions.
- Getting plenty of bright, natural light during the day has, in a recent study, been found to reduce the effects of exposure to blue-enriched light at night.
Can blue-enriched light be used to keep workers alert on night shifts?
It would be logical to assume, given the alerting and performance benefits of blue-enriched light, that exposure to it would be a great way for night shift workers to get through the tougher hours of their shift. Unfortunately, it has been found that chronic, inappropriately timed exposure to this kind of light can lead to circadian misalignment and eventually to sleep problems, depression and possibly even cardiovascular disease.
It’s not just about the light
Some sleep experts have pointed out that blue-enriched light is not the only reason that using electronic devices at night can have a negative effect on sleep. Activities such as playing games, checking email and surfing the internet, also act as stimulants, keeping our brains awake and active. So, if you must use an electronic device before going to sleep at night, use one of the blue-enriched light reduction strategies mentioned above and use the time to read a relaxing book. You’ll sleep better for it.
- Burkhart, K. and Phelps, J. R. (2009) Amber lenses to block blue light and improve sleep: A randomized trial. Chronobiology International, 26(8), 1602-1612.
- Cajochen, C., Frey, S., Anders, D., Spati, J., Bues, M., Pross, A., Mager, R., Wirz-Justice, A. and Stefani, O. (2011) Evening exposure to a light-emitting diodes (LED)-backlit computer screen affects circadian physiology and cognitive performance. Journal of Applied Physiology, 110, 1432-1438.
- Chang, A.-M., Aeschbach, D., Duffy, J. F. and Czeisler, C. A. (2015) Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness. PNAS, 112(4), 1232-1237.
- Gringras, P., Meddleton, B., Skene, D. J. and Revell, V. L. (2015) Bigger, brighter, bluer-better? Current light-emitting devices – adverse sleep properties and preventative strategies. Frontiers in public health, 3, 233.
- Rangtell, F. H., Ekstrand, E., Rapp, L., Lagermalm, A., Liethof, L., Bucaro, M. O., Lingfors, D., Broman, J.-E., Schioth, H. B. and Benedict, C. (2016) 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, 23, 111-118.
- Viola, A. U., James, L. M., Schlangen, L. J. M. and Dijk, D.-J. (2008) Blue-enriched white light in the workplace improves self-reported alertness, performance and sleep quality. Scandinavian Journal of Work and Environmental Health, 34(4), 297-306.
Conferences and presentations
USA Rail Crew Management & Timekeeping Conference (23-26 April 2017)
St Augustine, Florida, USA
Hosted by CSX Transportation, this conference is an annual event and features discussions around crew management and timekeeping issues that confront all the operators, including fatigue and FRMS. Staff from InterDynamics attended the conference, which also included representatives from Union Pacific Railroad, BNSF, Norfolk Southern, Canada National, Canadian Pacific, Kansas City Southern and AMTRAK.
ISPO Conference (21-22 June 2017)
Rotterdam, The Netherlands
The ISPO (International Standard for Maritime Pilot Organizations) is a standard of best practice for pilots and pilot organizations, improving safety and quality. Providing self-regulation and transparency in pilotage standards to all port related stakeholders. This year, the annual ISPO conference was held in Rotterdam.
InterDynamics’ staff gave a presentation on ‘Implementing a Fatigue Risk Management System’ at the conference.
In the News
Provided below are a selection of articles from around the web on the issues associated with fatigue. We hope you find them useful and interesting.
Dr Michael J. Breus, HuffPost (24 March 2014)
A new study further examines the stimulating effects of blue wavelength light, focusing on the effects of daytime exposure to the short-wavelength light. They also compared the daytime effects of blue light exposure to the effects of evening exposure to the same degree of light.
Reactions, YouTube (19 May 2014)
Your smartphone addiction isn’t helping you sleep. In fact, an obscure chemical reaction may be keeping you awake. The latest Reactions video looks at the process that connects your late-night texts to your lack of sleep.