Melatonin is the natural hormone our bodies produce that promotes sleep. Darkness signals our body to release more of it, while light causes production to stop. Melatonin regulates our 24-cycle of wake and sleep known as our circadian rhythm and synchronizes this cycle with night and day. That’s why those who do shift work often struggle with sleep — they are working in opposition to the natural sleep-wake cycle.
The invention of the lightbulb (thanks, Thomas Edison!) meant our schedule was no longer controlled by darkness — we could go to bed whenever we wanted. But exposing ourselves to bright light — even artificial light — when it’s nearing bedtime confuses our brain into thinking it’s seeing sunlight and throws off our natural circadian rhythm.
And then along came electronic devices. A Sleep in America poll found that 90% of Americans reported using an electronic device in their bedroom within an hour of trying to fall asleep. Electronic devices, from TVs to smartphones, e-readers and laptops, emit blue light. Of all the types of light in the spectrum, blue light has the greatest impact on our circadian rhythm, making us feel alert and elevating our body temperature and heart rate — all counter to falling asleep.
What can you do about it?
As you start winding down and getting ready for bed, consider your light sources. Reduce your ambient light, ideally switching to yellow-red lighting sources or even candles. Dimming LED and fluorescent light bulbs, which are also in the blue light spectrum, helps your wind-down as well.
But most importantly, turn off your electronic devices at least 30 to 60 minutes before going to bed. Keep in mind that these devices, in addition to the light they emit, may also have content that arouses you instead of allowing you to relax. Find other ways to relax, such as a warm bath or shower, meditation or reading a book (preferably one that isn’t too action-packed and exciting).
When you go to bed, make sure your room is completely dark (cover any light sources or wear an eye mask, if necessary). When you get up in the morning, expose yourself to natural light as early as possible as a signal to your body that it’s time to start your day. To get maximum exposure, avoid wearing sunglasses in the morning.
Sources: Sleep Foundation; Gradisar, M et al. (2013) The sleep and technology use of Americans: findings from the National Sleep Foundation’s 2011 Sleep in America poll, J Clin Sleep Med; Lockley, S et al. (2003) High sensitivity of the human circadian melatonin rhythm to resetting by short wavelength light, J Clin Endocrinol Metab; Vandewalle, G et al. (2009) Light as a modulator of cognitive brain function, Trends Cogn Sci; Wahl, S et al. (2019) The inner clock-Blue light sets the human rhythm, J Biophotonics.
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