How your phone is impacting your sleep cycles
During the daytime, sunlight blocks an important reaction in our brain that would usually cause serotonin (a chemical that makes you feel happy), to be converted into melatonin (a chemical that makes us feel sleepy).
The light hits the retina (back of the eye), goes to your suprachiasmatic nucleus (body clock) which stops any signals being sent to the pineal glands (the part of your brain that regulates sleep).
This is why it can very difficult to sleep during daytime unless you’re very tired.
In the absence of light (at night time) your brain converts some of your serotonin (the “happy” chemical) into melatonin (the “sleepy” chemical) in the pineal glands.
Melatonin is a useful chemical that smoothly transitions you from an awake to a sleeping state (like “switching off”).
This is also why as seasons change and the days shorten, it can be quite normal to feel sad as your brain adjusts to the shorter daylight hours, as it readjusts the serotonin release.
How does this relate to your phone? The blue light of your phone screen simulates sunlight, and actually tricks your brain that it’s day time when you’re staring at it in bed.
So phone manufacturers actually contacted medical professionals with this problem, who advised the use of a warm red-orange light instead, which doesn’t have such a potent effect, and hence the creation of “night time” settings on your phone!
If you’re struggling to sleep, try to avoid heavy screen use a couple of hours before bed and see if you notice any difference, alternatively melatonin can actually be prescribed by your GP if you’re having more serious difficulties.
Sam Fitzpatrick Final Year Medical Student, Cardiff University.
Milad Rouf Final Year Medical Student, Cardiff University.
Pocock et al. 2014, Human Physiology 4th Edition. Chapter 13, “Some Aspects of Higher Nervous Function.
Gringras, P., Middleton, B., Skene, D. and Revell, V. 2015. Bigger, Brighter, Bluer-Better? Current Light-Emitting Devices – Adverse Sleep Properties and Preventative Strategies. Frontiers in Public Health 3.