By If you are well versed with sleep medicine or seen a sleep medicine specialist, then you know that blue light isn’t good for melatonin, and it is not a good idea to use blue light devices in the evenings. Melatonin is a naturally produced hormone that helps with inducing sleep. Blue light devices hamper the release of melatonin since its production is linked with day/night variation, in fancy terms, regulated by the circadian rhythm.
For a long time we thought that eliminating blue light on smartphones using the night time mode would help. A recent study published in the Journal of Sleep Health [1], studied 167 individuals with iPhone to see if the nighttime mode made a difference in their sleep. These people were divided into 3 groups. One that did not use the phone at bedtime, one that used the phones at bedtime with night time mode on and the last group that used the phones at bedtime with night time mode off. The group that did not use the phones slept for 7+ hours and experienced better sleep quality than those who used the smartphones at bedtime. Regardless of using night time mode or not, the individuals who used smartphones had poorer sleep quality and duration. Hence, the night time mode made no difference. Hence interventions like night time mode or blue light filter glasses may not help with sleep.
This study points out the fact that sleep hygiene is of utmost importance for sleep. When using smartphones closer to bedtime, your sleep is disturbed. Blue light decreases the release of melatonin that helps you sleep better. And whatever activity you are engaged on, on the smartphone, stimulates your brain. We need a relaxed, calm, brain to be able to fall asleep. It would benefit more to have a more relaxing bedtime routine.
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References:
1. Duraccio, K., Zaugg, K., Blackburn, R. and Jensen, C., 2021. Does iPhone night shift mitigate negative effects of smartphone use on sleep outcomes in emerging adults?. Sleep Health,.