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Does using the “Night” mode on your smartphone improve sleep quality?

Night mode is a feature on many digital devices, and is designed to reduce the amount of blue light emitted from the device. It is based on the premise that exposure to blue light suppresses melatonin production in the brain, and hence, disrupts sleep and our sleep-wake cycle. The logic is: if Night mode is used, then we will have less exposure to blue light from the device, and our sleep will be unaffected after using the device.

Night mode goes by various names, including “Night Shift” (Apple products), “Night Light” (Microsoft Windows) and f.lux (an app you can download onto your device). It adjusts the colour temperature of the display to reduce the amount of blue light emitted from the display. The higher (or stronger) the setting, the less blue light emitted from the display, and the more orange the display appearance.

You can check if Night mode is installed on your device by looking in the device settings. This is what the “Night Light” settings look like in Microsoft Windows:

Does Night mode work?

Some people love the feature and say that it helps them sleep, while others say it has no effect at all. These differences can probably be attributed to the many factors that affect our sleep—not only blue light. For example:

  • A study published in 2019 [1] found that melatonin was still suppressed (and hence, sleep potentially delayed) when the Night Shift mode on an iPad was adjusted to it’s highest setting. Since display brightness can also affect melatonin production in our brains, the authors concluded that users should reduce the overall brightness of the display in addition to using Night mode.
  • A study published this year found that for people who averaged less than 6.8 hours sleep per night, it did not matter whether or not they used their smartphone before bed, or used the Night mode feature—their self-reported sleep quality remained the same [2].
  • The same study found that for people who averaged more than 6.8 hours sleep per night, sleep quality was better when they didn’t use their smartphone at all for 60 minutes before bed [2]. The Night mode had no effect on sleep quality. The authors concluded that cognitive tasks associated with smartphone use (for example, checking or replying to emails) probably delayed sleep, rather than blue light exposure.

References

  1. Nagare R, Plitnick B, Figuerio M. Does the iPad Night Shift mode reduce melatonin suppression. Lighting research and technology. 2019; 51(3):373-83.
  2. Durraccio K, Zaugg K, Blackburn R, Jensen C. Does iPhone night shift mitigate negative effects of smartphone use on sleep outcomes in emerging adults? Sleep Health. 2021; https://doi.org/10.1016/j.sleh.2021.03.005.

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Do you use your smartphone or tablet in bed? Read my Blog on the Work Journal website to find out some tips to improve your comfort, safety and sleep quality.

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