Struggle to nod off? (Dailymail Article)

Struggle to nod off? Don't take your phone to bed: Electronic devices reduce sleep-hormone levels

  • Blue light from digital devices lowers levels of melatonin which promotes sleep
  • Levels naturally begin to rise in the evening but screens alter internal body clock
  • People wearing blue light blocking glasses fell asleep faster and slept better 
  • They also got 24 minutes more shut eye each night, Houston researchers found
  • Experts recommend limiting screen time or applying screen filters

The screens from our digital devices disrupts sleep dysfunction by lowering melatonin levels, a new study has found.

The blue light they emit interferes with the hormone made naturally by our bodies which helps us control our sleep-wake cycles.

Normally, melatonin levels begin to rise in the mid- to late evening, remain high for most of the night, and then drop in the early morning hours.

But watching screens from phones and tablets late in the evening plays havoc with this process, by boosting alertness and altering our circadian rhythm – or our internal body clock.

Lead author Dr Lisa Ostrin from the University of Houston College of Optometry said: 'The most important takeaway is that blue light at night time really does decrease sleep quality. 

'Sleep is very important for the regeneration of many functions in our body.'

Insomnia is a common problem thought to regularly affect around one in every three people, and is particularly common in elderly people.

And the cost is more than just fatigue. Lack of regular sleep is linked to raised risk of depression, obesity, heart attack, stroke and diabetes – and it shortens your life expectancy.   

Key findings 

Researchers asked 22 participants, aged 17-42, to wear short wavelength-blocking glasses three hours before bedtime for two weeks, while still performing their nightly digital routine.

The findings showed a 58 percent increase in their nighttime melatonin levels.

Those levels are even higher than increases from over-the-counter melatonin supplements, says Dr Ostrin – highlighting how switching off our screens can achieve a more effective result. 

Wearing activity and sleep monitors 24 hours a day, the participants also reported falling asleep quicker and sleeping better.

The also increased their sleep duration by 24 minutes a night.  

Limit screen time or apply screen filters 

While light of any kind – natural or artificial – interferes with our body clock, blue light found in most LED-based devices at night does so more powerfully.


This artificial light activates photoreceptors called intrinsically photosensitive retinal ganglion cells (ipRGCs), which suppresses melatonin.

Dr Ostrin recommends limiting screen time, applying screen filters or wearing computer glasses that block blue light.

You can also use anti-reflective lenses to offset the effects of artificial light at nighttime, she said.

Some devices include a 'night mode' setting that limit blue light exposure.

'By using blue blocking glasses we are decreasing input to the photoreceptors, so we can improve sleep and still continue to use our devices,' she said. 

'That's nice, because we can still be productive at night,' Ostrin said. 

Natural melatonin levels slowly drop with age. Some older adults make very small amounts of it or none at all. 

During the shorter days of the winter months, your body may produce the hormone either earlier or later in the day than usual.

This change can lead to symptoms of seasonal affective disorder (SAD), or winter depression.

The research was published in the journal Ophthalmic & Physiological Optics.


November 08, 2018 by Boca Blu Admin Team

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