Blue Light and Sleep –What’s the Connection

Photo Credit: AlexanderFord

Have you ever wondered why you feel alert, active, and energized on bright, sunny days? And why do the rainy/winter days make you feel sluggish, tired, and sleepy? People may have different explanations for it, but science tells us that it has to do with exposure to blue light! The same blue light that laptops and cell phones are infamous for.

What is Blue Light, and How Is It Connected to Sleep?

Blue light is a high-energy light wave that vibrates between 380 and 500 nanometers and is one of the seven lights visible to the human eye. It makes up one-third of the visible light spectrum. Blue light has the shortest wavelength but the highest energy of all the lights that are a part of it. To give a bit of perspective to those who may not know, humans can only see a small band of electromagnetic waves that light is composed of, and they are all found in the rainbow. The rainbow shows all the colors of the visible light spectrum.

Why Are We Only Concerned About Blue Light?

The reason why we are concerned about blue light and not the other types of visible light on the spectrum is that it is the one least filtered by our eyes. We are also the most highly exposed to it. Human eyes cannot effectively block or filter blue light. This means most of the blue light we are exposed to reaches the retina. This, coupled with the fact that blue light makes a major chunk of the visible light spectrum, makes us more exposed to this high-energy light wave than the other types of visible light.

Is Blue Light Bad for Health?

Blue light, just like the sunlight, is not all bad for us. Our body needs some blue light to work at its best. However, too much blue light exposure can cause it harm, too. Let’s take a quick look at the key benefits and side effects of blue light to better understand how this short-length electromagnetic radiation affects our health.

Health Benefits of Blue Light

Blue light actually provides quite a few benefits. It can:

• Promote alertness

• Improve mood

• Boost memory

• Enhance cognitive function

• Improve symptoms of seasonal depression

Blue light also plays a vital role in regulating (or ruining) our natural sleep-wake cycle (circadian rhythm). And this is how it’s connected to sleep.

The Harmful Effects of Blue Light

Excessive exposure to blue light is a growing concern in health circles due to the adverse effects it can cause. Some of the most commonly reported health problems associated with too much blue light exposure include:

• Inability to sleep/ poor quality sleep/ disruption of the sleep cycle

• Eye soreness

• Dry eyes

• Headaches

• Trouble concentrating

• Reduced productivity

Though not proven, there’s some evidence that excessive exposure to blue light may cause damage to the retina.

Exploring the Connection between Blue Light and Sleep

Blue light plays a key role in promoting alertness. Excessive exposure to it, particularly in the evening, can interfere with melatonin production, making it difficult to fall asleep.

Continuous exposure to too much blue light can also disrupt sleep quality and interfere with our sleep-wake cycle. The opposite is also true. When our body doesn’t get an adequate amount of blue light, we may feel more tired and less active. This is one of the reasons why we feel dull, lazy, and sleepier in winter months or on cloudy days when the sun isn’t fully out.

Sleep and Blue Light – A Deep Dive

Presuming that not all of our readers may have the background knowledge needed to understand what we just discussed, here’s a simpler, more detailed explanation of the connection between blue light and sleep…

Circadian rhythm is the scientific name of the 24-hour biological clock in our body that influences and regulates several internal functions. While there are internal factors involved in keeping this clock running right, it also takes signals from the outside for several tasks. Sleep is one of them.

The internal clock takes cues from the (blue) light in the surroundings to tell the body when to sleep and wake up. Since the high amount of blue light in the surroundings is a sign of daylight, the body responds by promoting wakefulness, even when the light source isn’t the sun.

Our body can’t differentiate between blue light coming from the sun or other (artificial) sources. It just senses the amount of light in the external environment and triggers the corresponding action.

Exposure to blue light at night delays or hampers the natural process of melatonin secretion. Melatonin is a hormone that tells your body it’s time to go to sleep. When it isn’t produced on time or in an adequate amount, your sleep cycle gets disrupted. When this continues, you become prone to developing sleep disorders and several other health issues. Several studies have shown that continuous suppression of melatonin during the evening hours can lead to health problems. The ones that are most likely to result include:

• Depression

• Obesity

• Metabolic syndrome

• Cardiovascular disease

There’s also some evidence that disruptions in circadian rhythm may even put you at an increased risk of developing cancer.

Effects of Blue Light on Sleep – The Scientific Proof

A study conducted by a group of Harvard researchers found that the effects of blue light on melatonin secretion and circadian rhythm are twice as stronger as green light of comparable brightness. The study revealed that exposure to blue light delayed melatonin secretion and pushed back the sleep cycle for twice as long as the green light.

Where Does Blue Light Come From?

Sun is the biggest source of blue light. This high-energy light makes up about 25% to 30% of sunlight during the day. Sun is also the only natural source of blue light. But it is not our only source of blue light today. Much of our blue light exposure now takes place via:

• Lighting sources, such as fluorescent bulbs, compact fluorescent lamps, and LED lights

• Flat-screen televisions

• Digital devices – computers, laptops, tablets, cell phones, and gaming devices

The widespread adoption of LED technology has drastically increased human exposure to blue light. From computers, laptops, and mobile phones to the television and lighting fixtures in our homes, all use advanced and energy-efficient LED technology, putting us at a significantly higher risk of experiencing the harmful effects of blue light.

Four Ways to Limit Your Blue Light Exposure

Here are some scientists-recommended strategies to limit blue light exposure at night and its adverse effects on sleep:

1. Avoid Screens before Bedtime

The simplest and the most effective way of reducing your blue light exposure is to stop using electronic devices, like TV, computer, phone, and gaming consoles, about an hour or two before bedtime. If that’s not possible, health experts recommend giving yourself at least 30 minutes off-screen before bed.

2. Adjust Screen Lighting

When using the screen at night becomes unavoidable, you should change the screen to ‘night mode’ to change the bright light to warmer tones. You may use blue light screen filters. Research shows that they may reduce blue light exposure by 30% to 60%.

3. Install a Blue Light Filtering App on All Your Digital Devices

Considered an advanced version of blue light filtering screens, these apps effectively reduce the amount of blue light that reaches your eyes. The best part? They do so without affecting the quality of the display.

4. Avoid Using Bright, White Lights in Your Bedroom

Even if you have them, turn them off at nighttime. Use an orange or red task or accent lighting for bedtime activities, like reading. Red light has the least effect on melatonin and circadian rhythm.

Get Plenty of Sunlight to Ward-Off Blue Light Effects

If your sleep cycle is already affected by blue light, exposing yourself to plenty of sunlight during the day, along with limiting your exposure to it during the evening hours, can help fix it.

The Sum Up

Sleep is one of the most crucial requirements for staying healthy. Despite it being a widely known fact, an increasing number of people are now sleeping less than the recommended amount. Many are also struggling with poor-quality sleep. While there are several reasons behind the increasing prevalence of sleep problems, excessive exposure to blue light during the evening hours is a major contributing factor. It tricks your brain into believing that it is still daytime. Thus, delaying the release of melatonin and disrupting the sleep-wake cycle. If you can’t avoid it, limit your exposure to blue light at night to avoid disrupting your sleep and health.