What time of day should I limit Blue Light

What time of day should I limit blue light?

We should limit blue light 2-3 hours before bedtime in order for our body to produce melatonin which aids in the sleep process. We should also limit exposure to blue light from digital devices throughout the day to avoid digital eye strain and other issues.

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Did you know that the primary source of light is our sun? That means we are exposed to far more blue light in the day than at night.

We are always constantly reminded of blue lights’ harms and potential hazards, but do we need to protect ourselves from the blue light every time?

The answer is NO! The blue light emitted from the sun during the daytime can be beneficial.

How is blue light from the sun beneficial you may ask?

Its boosts mental alertness and cognitive function and regulates your body’s natural waking and sleeping cycle.

We need blue light to make us alert during the daytime.

So, what should be the time of the day that we need to limit blue light? We will discuss it in this article.

What is the effect of blue light in the day time?

We, humans, are programmed to say active and alert during the evolution course in the daytime while retiring and off to bed at night.

Blue light is the main factor in programming our sleep and wake cycle. Sleep forms part of our circadian rhythm.

Our circadian rhythm is a 24-hour cycle that includes physical, mental, and behavioral changes that happen over this period or in simpler terms our “body clock”.Sleep makes up a significant part of this cycle 

How does blue light affect it?

Exposure to blue light reduces the sleep-inducing hormone in our body, called melatonin which in turn affects our ability to fall asleep and get a good night’s rest.

Blue light also enhances our cognition and boosts our mood so that we are active in performing our daytime functions.

Exposure to natural blue light from the sun regulates circadian rhythm was in simple terms is our body’s ability to wake and sleep. If we go deeper into this we can say it helps produce Serotonin and dopamine which are called “neurotransmitters”.

Serotonin and dopamine neurotransmitters affect mood, sleep, appetite, cognitive function, and mobility. 

Whilst we need blue light to create serotonin and dopamine we also need darkness or lack of blue light to create the neurotransmitter melatonin which is responsible for helping us to relax and go to sleep.

Therefore, it is recommended we limit our blue light 2 – 3 hours before going to bed to allow downtime and the production of melatonin which will help us fall asleep more easily. 

What effect does blue light have at night?

At night our bodies are programmed to dose off. How?

Lack of blue light causes melatonin expression on our bodies, and this melatonin will induce sleepiness. 

However, this is not the case in recent times. With modern-day digital devices and other illumination sources like fluorescent bulbs and LEDs, the exposure of blue light has increased way past the sunset.

This untimed blue light exposure has led to a decrease in melatonin production and hence more alertness at night. 

The use of digital devices before bed tricks our bodies into thinking it is daytime and that we should be more alert. 

How does this happen?

When you go to bed do you ever feel the need to send that last text into your WhatsApp group or check Facebook, tik tok, or Twitter to see what’s the latest craze?

When we do this we are consuming blue light from our mobile phone which is sending signals to your brain to be more alert and awake rather than dosing off quickly. 

A way to mitigate or prevent overconsumption of blue light at nighttime is to incorporate the use of blue light blocking glasses into your daily routine.

These simple steps can have a positive impact on many other aspects of your life.

As we have described previously every element of the body is interlinked (Ciarcidian Rythm) and each action we undertake will have a positive and negative impact on our daily lives depending on our choices i.e. by limiting blue light at night time before bed can lead to better sleep and being more alert and productive the following day.

What are the health impacts of blue light exposure at night?

Sleep is one of the necessities for optimal health. However, the sleep quality and quantity both are decreased in current times.

The culprit? It is excessive exposure to blue light at night. There are many health impacts on this untimed blue light exposure.


Yes, insomnia is one of the primary sleep issues we are facing these days. The more exposure to blue light at night, the less the expression of sleep-inducing hormone melatonin means less sleep and more alertness.

When we take about sleep we must look at sleep quality and sleep quantity. It is recommended we get at least 7 hours of good quality sleep per night. 

Sleep quality is translated using 4 different stages of sleep:

  1. Time Awake
  2. REM – Rapid Eye Movement 
  3. Light Sleep
  4. Deep Sleep

Each stage of sleeping provides different functions for the body and mind.

“Time Awake” is self-explanatory – this is the time we go to bed and lay there awake trying to get asleep or if we are woken during the night, it is the time spent trying to get back asleep

“REM” or “Rapid Eye Movement” is the time your eyes move around rapidly while you are sleeping. This stage of the sleep cycle is important for learning and retaining memories.

During this stage of sleep, no visual information is transmitted to the brain. On average is makes up approx 20-30 percent of your night’s sleep.

“Light Sleep” is the time we transition from being awake to falling asleep. This typically makes up 50% of our night’s sleep.

Light sleep is essential for allowing the body to transition into a “deep sleep”.

“Deep Sleep” is the time our bodies are fully relaxed and in recovery mode. It is the point of sleep where our brain waves and the whole body slows down.

It is essential we try and aim for 1-2 hours deep sleep per night.

Deep sleep is the stage of the sleep cycle that gives you that refreshed and recovered feeling when you awake in the morning 

Tiredness at daytime 

Our body and brain need time to get recharged after a tiring day. We need to sleep to regain our mental and muscular strength back.

However, with the lack of sleep, our bodies feel tired and our mind fogged. Thus, we won’t be able to carry out our daytime functions usually.

Eye strain and soreness

Ever felt tired and heavy eyes after prolonged use of computer screens or and smartphones. This is due to continuous blue light exposure on our eyes.

We are practically glued to our digital devices these days, and using our cellphones late till night is a routine for most of us.

This excessive usage is costing us our eye health. Dry eyes and eye pain are all the digital eye strain symptoms caused due to excessive blue light exposure.

How can we limit the blue night at night time?

We can adopt some measures to decrease our blue light exposure at night and save ourselves from various health hazards.

Adjusting the brightness level at night 

We should adjust the brightness of our phones and other digital devices at night. Some apps are available that would reduce the harmful blue light emission.

Using blue light blocking glasses

Blue light blocking glasses have become an inevitable purchase these days. We can use these glasses while working on our digital devices or generally while we are out and about. 

These blue light blocking glasses does not let an excessive amount of blue light exposure on our eyes hence helping us to reduce the overall health impacts of blue light. 

Turning lights off one to two hours before bedtime

We need melatonin expression for sleep induction. LED lights and fluorescent bulbs emit blue light, which causes the suppression of melatonin expression.

It’s always a good idea to dim or turn off our lights before bedtime for a sound sleep.

Limiting screen time

Yes, the best measure is to limit the screen time altogether. We spend hours on our phones way past our bedtime without even realizing the potential damages.

When To Use Blue Light Filters

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