We all know the benefits of a good night’s sleep. Yet how often do you wake feeling fantastic and ready to tackle the day? We’ve written before about how to improve sleep, but if you spend your last waking hours in front of a screen you may be giving yourself a problem.
Near the centre of our brain, tucked between the folds of an important structure called the thalamus, we have a small endocrine gland called the pineal gland. When light-sensitive cells in the eye’s retina detect light, a signal is sent to a tiny region called the suprachiasmatic nucleus, which is important for synching our bodies with nature’s 24-hour light/dark cycle. Nerves from the suprachiasmatic nucleus travel through several different tracts and eventually reach the pineal gland. At night, when it’s dark, the pineal gland is activated to produce a hormone called melatonin, which promotes feelings of sleepiness.
Although all wavelengths of light suppress melatonin production, the pineal gland is particularly sensitive to light in the blue range (460-480 nanometers). This is the light emitted by smartphones and tablets. In a 2006 study by Steven Lockley at Harvard University, 16 healthy adults were exposed to 6.5 hours of either blue or green light. Compared to green light, blue light exposure suppressed melatonin production for more than twice as long (90 versus 40 minutes).
Blue light was also associated with decreased feelings of sleepiness and decreased delta (“slow-wave”) brain activity while awake, suggesting that blue light enhances alertness both subjectively and objectively.
Unfortunately for us, the alluring glow of our digital devices is primarily composed of blue light – and given the enormous percentage of the population that uses a smartphone or tablet computer at least one hour before bedtime – it is having an enormous impact on sleep patterns. In December, Penn State University’s Professor Anne-Marie Chang and Harvard colleagues reported that, compared to reading a paper book before bed, iPad use increases the time it takes to fall asleep, decreases rapid eye movement (REM, or dreaming) sleep and decreases feelings of sleepiness in the evening as well as alertness the next morning.
In an article published in the online publication The Conversation, the author did an experiment where she wore orange-tinted glasses (or ‘blue-blockers’) for an hour before going to bed instead of looking at computer screens. In summary, she increased her average nightly sleep time by 20 minutes per night and woke feeling more refreshed.
While it was only a study by one individual, the results were such that you may consider trialling orange-tinted glasses before bed if you struggle to sleep at night. Maybe you just don’t realise your sleep patterns are not as normal as they should be because of your computer habits before bedtime?