We all do it; texting, emailing, reading articles, watching TV, sitting up in bed till midnight staring at any number of electronic devices, hell i’m doing it right now. It’s become ingrained in us to check our phones and tablets before we shut down for night, but what are the effects of all this screen time on our health?
Research tells us that all the night time light exposure, specifically blue light exposure is having significant effects on our health by disrupting our circadian rhythms and quality of sleep. Circadian rhythms are an internal cycle of processes that are influenced by external cues, such as eating, nutrition, exercise, temperature and in particular light and dark.
Poor sleep quality is becoming an increasing problem in the western world, with ever increasing working hours, long daily commutes, complex families, and the ever present entertainment industry it is easy to loose those long restful nights we once had. Now linked to heart disease, type 2 diabetes, depression, and as a strong risk factor for obesity, good quality sleep, or lack thereof is proving essential for health and optimum function.
It’s not just quantity of sleep hours but also the quality of the sleep that we are getting that is impacting upon our health. Research tells us that all the night time light exposure, specifically blue light exposure is having significant effects on our health by disrupting our circadian rhythms and quality of sleep. Circadian rhythms are an internal cycle of processes that are influenced by external cues, such as eating, nutrition, exercise, temperature and in particular light and dark. These cues alter our physiological rhythms or cycles to fit in with our surrounding environment.
Light plays a particularly important role in the regulation of the sleep cycle (amongst others). For a long time natural light was the only form that effected the flora and fauna on the planet, and every living organism from bacteria to humans developed patterns and cycles to coincide with the light dark cycle of the earth. Now manmade lighting has a huge impact upon our lives, from street lights to TVs to alarm clocks. Our basic physiological processes cannot determine the difference between blue light from a bright sunny morning sky and blue light from an ever scrolling Instagram feed at 2am. For this reason those two widely different inputs start the cogs turning of the same biological reaction within the body.
It is specifically blue light that effects our sleep wake cycles in this way. Blue light in particular can be perceived by a third type of non visual photoreceptor in the eye (not rods or cones) that are uniquely sensitive to blue – melanopsin retinal ganglion cells. These cells have a direct pathway to the brains master clock (suprachiasmatic nucleus), which is in turn connected to the pineal gland; the organ that secretes melatonin into the bloodstream.
When blue light is perceived the secretion of a hormone called melatonin is suppressed. So when there is little blue light more melatonin is secreted and when there is a lot of blue light less melatonin is secreted in the body. Natural blue light from the sky suppresses melatonin release and this helps us to remain alert and awake during day hours. When the sun sets and this natural light disappears melatonin production would naturally increase causing the desire and need for sleep.
Increased night time blue light exposure suppresses the secretion of melatonin, maintaining our level of alertness into the night time and increasing the length of time it takes before the onset of rapid eye movement (REM) sleep by roughly 30 minutes. The increased use of blue light devices is being linked to the growing number of sleep disorders (U.S data).
So how do we avoid these negative blue light effects?
- Avoid using your TV, computer, phone, or tablet for an hour before going to bed.
- Sleep in the dark, or as close to complete darkness as possible. Even the glow from your alarm clock can disrupt your bodies biological clock, so cover it up, move devices away form the bed and invest in some good drapes or an eye mask!
- Get daily sun exposure; the amount of melatonin produced is in part due to the comparative level of light to dark experienced throughout the day. So if you sit in the dark all day there won’t be much change when it’s time to get some shut eye.
Setting good sleep habits for infants and children is particularly important for their growth and both physical and mental development. Remove all blue light stimulus two hours before bedtime, if possible, to help with development of sleep patterns and circadian rhythms.
Now that you’re aware of it, creating good sleep patterns is a relatively easy component of a healthy primal lifestyle. Not as disruptive as altering your diet or as difficult as adapting to increase movement and exercise. Switching off an hour before bed and blocking out any excess light can improve your health and hey you’ll probably even witness the positive effects at work and in social situations too!
- http://dx.doi.org/10.1093/eurheartj/ehr007 (2011). Sleep duration predicts cardiovascular outcomes: a systematic review and meta-analysis of prospective studies. In European Heart journal. Vol. 32(12) PP. 1484-1492. Retrieved from
- Cappuccio, F. P., D’Elia, L., Strazzullo, P., & Miller, M. A. (2010). Quantity and Quality of Sleep and Incidence of Type 2 Diabetes: A systematic review and meta-analysis. In Diabetes Care, 33(2), 414–420. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2809295/
- Alvaro, P. K., et al. (2013). A Systematic Review Assessing Bidirectionality Between Sleep Disturbances, Anxiety, and Depression. In Sleep. Vol. 36(7). Retrieved from http://www.journalsleep.org/ViewAbstract.aspx?pid=29009