Late-night TikTok watchers can breathe a sigh of relief, as a new study has claimed that the light emitted from smartphones does not have a significant effect on sleep quality.
It has long been advised that those hoping to get a quality night of sleep should avoid using devices such as phones and tablets, and watching TV before bed because of the blue light they produce.
Blue light has been said to suppress melatonin, which is the light-reactive hormone that assists sleep and a human’s circadian rhythm, or internal 24-hour clock.
However, a new report published in the medical journal Sleep Medicine Reviews has questioned this conclusion, stating that the effect of screens on the ability to fall asleep is not as great as we think.
“If we stand back and look at all of the factors that can be harmful to our sleep, screens are overrated,” said Michael Gradisar, a clinical psychologist who co-wrote the paper.
“There’s no evidence from 11 studies conducted across the world that screen light in the hour before bed makes it harder to fall asleep.”
As reported in The Times, the biggest effect was seen in one study carried out a decade ago, which found that screens delayed people getting to sleep by only 10 minutes.
“One has to ask, does 10 minutes really make a difference?” Gradisar said.
According to Gradisar and the researchers, the most crucial factor that affects a person’s sleep is the time they finally nod off. This may suggest that it is a person’s distraction by the device, delaying their slumber, rather than the device itself that impacts sleep.
Still, many researchers note that screen light may affect people differently, with some reacting more strongly to its effects.
Russell Foster, professor of circadian neuroscience at Oxford who isn’t connected with the study, has also downplayed the impact of blue light on sleep, adding: “There’s no evidence that the blue lights from screens have any significant impact at all.”
Earlier this year, a study by the University of Basel recorded similar findings and suggested that screen blue light does not greatly affect a person’s sleep-wake cycle.
Dr Christine Blume, a psychologist at the Swiss university's Centre for Chronobiology, explained to Medical News Today that blue light itself is not massively important on a person’s sleep rhythm, but recommended that people reduce their exposure to short-wavelength light in general, regardless of its colour.
“Our results support the findings of many other studies that the light-sensitive ganglion cells are most important for the human internal clock,” Blume said.
“Therefore, short-wavelength light – misleadingly often termed ‘blue light’ – should be reduced in the evening, for example by dimming computer screens and using a night-shift mode.
“Avoiding screen time before bed can also help, as the things we do on our phones often delay sleep.”
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