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To understand why your phone can interfere with melatonin, we must first understand how melatonin works.

How does melatonin work?

Melatonin is a natural sleep-inducing hormone produced by the pineal gland in your brain. This hormone helps to regulate your circadian rhythm, a natural process that influences your daily sleep-wake cycle. Melatonin secretion3 increases as your body senses it’s getting dark, and the hormone is present in high amounts throughout the night to promote sleepiness. In contrast, the amount of melatonin is much lower throughout the day to promote wakefulness.

Remember: melatonin can be a short term option for sleep issues. If you have ongoing sleep difficulty, speak with your healthcare provider before continuing to use over-the-counter sleep aids.

What is blue light?

Light is made of small particles called photons.4 These particles travel in waves that vary in length. Longer waves transmit less energy, while shorter ways transmit more energy.

The types of waves in the electromagnetic spectrum5 include:

  • radio waves

  • microwaves

  • infrared

  • visible light

  • ultraviolet

  • x-rays

  • gamma rays

The human eye can only perceive visible light. If you refer to the visual below, you may notice that blue light has one of the shortest wavelengths in the visible light spectrum.

Source: Khan Academy
Source: Khan Academy

Where does blue light come from?

Common sources of blue light include:

  • the sun

  • digital screens (i.e. TVs, laptops, smart phones, tablets)

  • electronic devices

  • fluorescent and LED lighting

How does blue light affect sleep?

Because blue light has very short wavelengths, they transmit more energy. Blue wavelengths are helpful during the day because they boost attention, reaction times, and mood.7 In contrast, these wavelengths can be disruptive at night.

Constant exposure to blue light at night can make it difficult to fall asleep. In fact, light (even when dimmed) can affect melatonin production. This is why sleep specialists recommend staying off your phone or laptops before bedtime.

Tips to protect yourself from blue light at night

  • Use dim red lights as night lights.7 Red light has much longer wavelengths and is less likely to suppress melatonin production.

  • Avoid using bright screens starting a couple hours before bedtime.

  • If you must use your phone, or other device, turn on its night shift setting. When night shift is active, your phone adjusts the display to a warmer colored screen during evening hours, filtering out blue light.

  • Invest in a pair of blue-blocking glasses.

  • Get some sunlight in you! Exposure to a lot of bright light during the day can boost your attentiveness and mood throughout the day and make it easier to fall asleep at night.

To read more about using melatonin for jet lag, insomnia, and delayed sleep-wake phase disorder, check out I can’t sleep! Is melatonin a choice for me?