Lights Out

Recharge


If you’re struggling to get more sleep, you’ve probably heard that you should avoid screens like TV, tablets, and phones before bedtime. Light from screens can negatively impact your body’s circadian rhythms, tricking your body into thinking it’s daytime.

How do screens trick your brain? Initially, they are tricking your eyes. Do you remember learning about rods and cones in high school biology? These are two types of eye cells that gather light to enable sight. The cells in the retina also contain photosensitive retinal ganglion cells (ipRGCs) that allow your pupils to respond to light and synchronize your circadian rhythm to a 24-hour cycle.

When artificial light hits your retina after the sun has gone down, these parts of your eye interpret the light incorrectly, and your body receives the wrong information about time-of-day. This activates the hypothalamus and suppresses the hormone melatonin.

This chain reaction makes you feel less sleepy and more alert, making it hard to get the sleep you need.

So, to care for your brain, be kind to your eyes at night. Try low light activities in the hour before bed like reading a book, listening to a podcast, or writing in a journal. Getting a good night’s rest is an important part of caring for your brain and cognition.

References

  • Czeisler, C. Perspective: Casting light on sleep deficiency. Nature 497, S13 (2013). doi: 10.1038/497S13a
  • Eisenstein, M. Chronobiology: Stepping out of time. Nature 497, S10–S12 (2013) doi: 10.1038/497S10a
  • Ju YE, Lucey BP, Holtzman DM. Sleep and Alzheimer disease pathology—a bidirectional relationship. Nat Rev Neurol. (2014) 10:115–9. doi: 10.1038/nrneurol.2013.269