How Light Effects Circadian Rhythm, the Quality of Your Sleep and Health

When it comes to advancements in lighting solutions, Human Centric Lighting (HCL) applications are driving innovation at LEDdynamics.  Through technological refinements, the maximum levels of energy savings from LEDs have been mostly achieved across the industry.  Now, for the team at LEDdynamics, our R&D has shifted to engineering a commercially viable tunable white LED technology that can harness the power of sunlight to improve our health and wellness.

Now more than ever we’re living life indoors under artificial light, which is negatively affecting our health and wellness. A typical tunable white lighting system, with its ability to dynamically shift color temperature, does gets us one step closer to replicating sunlight. However, the purpose of this article is not to debate if tunable white light provides the benefits of circadian lighting, but to go into detail about and understand how light, in general, affects our circadian rhythm and the dramatic effect it can have on our sleep and overall health.

The Importance Of Circadian Rhythms

To understand the benefits of circadian lighting, it is vital to first understand the function of the human body’s circadian rhythm. The circadian rhythm is controlled by the brain’s hypothalamus. Connecting the nervous system to the endocrine system (the system responsible for hormone regulation), the hypothalamus operates via a small bundle of cells called the suprachiasmatic nucleus (SCN). The SCN is connected to the optic nerve behind the eye and receives information about the varying levels of light and darkness from our environment throughout the day and night.

When light enters your eyes first thing in the morning, the SCN responds immediately and kick-starts its “daytime mode”. Signals are sent that raise your heart rate, your temperature, and your blood pressure to wake you up and get your body moving.

Circadian SCN & Eye

Among waking up, circadian rhythms signal your body to engage in various actions, such as when to rise, eat, sleep, letting your body know when you’re most alert, and many other vital biological functions.

These rhythms also tell your body to delay the release of hormones like melatonin. Melatonin is a hormone released by the pineal gland that helps induce feelings of tiredness and promotes good quality sleep.

Unfortunately, in our always-on, digital world, our rhythms can get a bit out of sorts. If your circadian rhythm is out-of-sync with your daily schedule (also known as being “not entrained”), then it is likely that the time you wake-up and fall asleep each day will be delayed by increasing 15-minute intervals.

For the average person to feel healthy and energized each day, the National Sleep Foundation recommends between seven and nine hours of sleep every night for adults. Unfortunately, it is estimated that at least two-thirds of people around the world are not getting the recommended amount of sleep to live productive, energized lives. Globally, this is a significant percentage. If you are routinely getting less than eight hours of sleep, you are likely damaging your health and well-being without even noticing.

Two Types of Sleep: REM & NREM

At night, your body experiences two types of sleep rhythms – NREM and REM sleep.

Stage three of NREM is the beginning of deep sleep. This is the most restorative stage of sleep where your body works to repair muscle and tissue as well as build energy for the next day.

After stage three of NREM comes REM sleep, an acronym of Rapid Eye Movement sleep. REM is also known popularly as the dream state. At this stage in your sleep cycle, your eyes will often jerk quickly in different directions, your breathing becomes irregular, and your blood pressure and heart rate increase. Brain wave activity during this stage of sleep looks almost identical to your brain waves while awake. REM sleep is important for memory function and learning because at this stage of sleep your brain consolidates and processes information you encountered the day before.

For perspective, it takes your body approximately 90 minutes to cycle through all sleep stages. So, if you fall asleep at 9:00 p.m. you’ll enter REM sleep around 10:30 p.m. You repeatedly cycle through these stages at night, storing memories and repairing muscle damage, until you wake up the next morning.

Light Source Effects on Circadian Rhythm and REM Sleep

Your circadian rhythm plays an important part in ensuring proper access to REM sleep stages. If your circadian rhythm is not synced to the natural rhythm of the world around you, there can be physical, mental, and behavioral consequences. Lack of proper circadian regulation can cause insomnia or excessive daytime sleepiness – a symptom similar to that of jetlag.  In some cases, excessive sleep alterations can even cause nausea, irritability, and depression. (For a comprehensive list and explanation of negative effects read to the end of this post.)

In our 24/7 digital world, we often continually receive light into our eyes well beyond sunset. This can be in the form of household lighting like lamps and ceiling lights, or from our backlit screens like TVs, smartphones, and tablets. A study published in the journal PLoS One found that excessive screen time beyond the earth’s natural rotation light cycle is associated with poor sleep quality. Many of our devices give off a bright, artificial light that can negatively impact your circadian rhythm by tricking your body into believing that it is still daytime. This causes a delay in natural sleep processes such as the secretion of melatonin – the natural signal to your body to prepare for sleep. However, it’s not simply exposure to light that can alter the natural circadian rhythm, but also the wavelength of light that can be detrimental.

The Influence Of Light Wavelength

The visible light spectrum runs from 380nm to 780nm, with each nanometer representing a wavelength of light. At the high end of the spectrum (closer to 700) you find red light, and as you move through the rainbow of visible colors, the wavelength becomes shorter and shorter, ending with blue/violet light. Blue light is at its strongest in the morning and during daylight hours. This occurs because sunlight contains all the wavelengths of visible light, but since blue light is shorter, it is scattered more easily.

Blue light – found at 460-480 nm in wavelength – will suppress the biosynthesis of melatonin and keep us feeling alert. Interestingly, beyond 530nm melatonin production is not suppressed, even in bright light conditions.

In the early morning or late evening (sunrise and sunset), the sun is much lower on the horizon and therefore the light must pass through more particles to reach your eyes. This means that much of the blue light is lost before it reaches your eyes, and only long-wavelength red light is left to reach you. This influx of red light triggers your body to begin to produce melatonin so you can stay synced with the day/night cycle and begin to feel tired. Unfortunately, many artificial lights work against this natural cycle, emitting blue light in wavelengths that can suppress melatonin production, and therefore keep us feeling alert longer than it should. Prolonged exposure can shift our circadian rhythm out of its natural cycle.

A Harvard study found that after 6.5 hours of blue light exposure, melatonin was suppressed twice as long as when exposed to the green light for the same period. Circadian rhythms were also shifted 3 hours with blue light and 1.5 hours with the green light. When you consider the prevalence of blue-light emitting LED screens in the hours running up to sleep, it’s easy to see how you can shift your rhythm without realizing it – until it’s too late and your cycle has been damaged.

The biggest factor contributing to your circadian rhythm is light. However, it ’s extremely important to understand that lighting characteristics affecting your circadian rhythm can be different than those affecting your ability to see.  For example, the light that enables sight could also be used to signal your circadian rhythm that it is evening.

The people most likely to have out-of-sync circadian rhythms are those that spend a lot of time indoors and under dim light for extended periods of time. This environment is common with office workers and puts these individuals who work long hours indoors without windows to allow natural light into the room at high-risk for circadian rhythm damage.

Dr. Mariana Figueiro, professor and director at Lighting Research Center at Rensselaer Polytechnic Institute has been researching and educating people on how to synchronize their circadian rhythms for years. She describes Circadian Rhythm as a “blue sky” (short wavelength) detector.  Figueriro uses a great example related to camping that illustrates this concept:

Our pre-artificial light ancestors were in daylight first thing in the morning and shrouded in darkness after sunset, naturally syncing their Circadian Rhythms with the solar day. Based on this, Figueiro suggests that if you have ever been camping, you will probably begin to wake up with the sunrise and fall asleep with the sunset after only a couple of days in this sun-cycle.

Most of us now work and live comfortably inside, alongside constant artificial lighting instead of the cyclical nature of sunlight.  This non-stop, artificial light is one reason why two-thirds of us report disrupted sleep and ongoing sleep disorders.  Staying up after dark probably means that you are exposed to even more artificial light, only compounding the disruption to your Circadian Rhythm.

The Treatment of Circadian Rhythm Disorders

Luckily, most circadian rhythm disorders are treatable.

Dr. Figueiro and the LRC have developed the Circadian Stimulus (CS) metric to quantify light’s effect on the human circadian rhythm system. The team describes CS as a metric based on the extent to which a given light source – of specific amount and spectrum – suppresses Melatonin. The following light-related metrics, measured with CS, can help determine the source of sleep disturbance, and lead to a solution for treating sleep issues:

  1. Spectrum – Specific correlated color temperature (CCT) or wavelength of the light
  2. Light Levels – Proximity of light in relation to your eyes
  3. Timing – Time of day when you are receiving specific CCTs
  4. Duration – Length of time receiving specific CCTs

As Figueriro and the team’s study suggests, the higher each of these four metrics is, the more likely one is to experience issues. The increased amount and higher spectrum of light exhibited by frequent, extended exposure to artificial light sources can lead to disrupted circadian rhythms and an increased risk of rhythm-related sleep disorders. By implementing restrictions on this type and source of lighting in the times of the day that our bodies are naturally built to begin emitting melatonin, we can retrain our bodies to return to a natural cycle.

The Negative Effects of Sleep Disorder (Misaligned Circadian Rhythm Disorder)

Weight Gain

Weight gain has been associated with a lack of sleep for a number of reasons.

First, you’re more likely to make less healthy choices when you’re low on energy. For example, if you didn’t get enough sleep the night before, the first thing you’re likely to do is to load up on caffeine and carbohydrates to gain quick energy. This may be in the form of a simple cup of coffee or several of your favorite lattes. It’s also harder to resist sugary snacks such as donuts because you know they’ll give you a burst of energy from the sugar rush.

Second, if you’re already feeling tired, it’s unlikely you’ll be heading to the gym for a workout. Instead, you’ll want to go home and curl up in front of the TV. Exhaustion related to sleep-disorders can lead to poor health decisions that continue to damage the body.

Impulse Control

Sleep deprivation also impacts your impulse control. A study published in the American Journal of Clinical Nutrition found that when people experienced sleep deprivation, their late-night snacking increased and they were more likely to choose high-carb snacks for a quick-fix. You’re more likely to choose these unhealthy options because your body is looking for a boost of energy.

Impaired Brain Function

You may be surprised to learn that sleep deprivation affects the brain at a cellular level. A study published in Nature Medicine found that a lack of quality sleep makes it more difficult for brain cells to communicate with each other. This will result in increased mental lapses and impaired memory recall.

You’ve likely experienced this impaired mental state when sleep-deprived. In these moments,  you start struggling to focus and concentrate on a task because your mind is “foggy”. If you’re routinely finding it difficult to concentrate during the day, take a look at your sleep habits and make sure you’re getting enough rest at night.

Weakened Immune Function

Sleep is very important for a proper immune system function. When you sleep, your immune system produces proteins called cytokines. Cytokines are directly involved in the process of targeting infection and inflammation in your body. A lack of sleep also results in fewer antibodies in your system to fight off illnesses.  Proper lighting is critical for assisted living facilities where seniors are already more susceptible to health issues, and have trouble sleeping due to constantly on lighting.

If you’ve been looking for a natural way to boost your immune function and reduce your risk of illness, getting the recommended seven to nine hours of sleep every night is a great place to start.

Reduced Athletic Performance

Sleep is crucial to successful athletic performance. You may have heard people compare being sleep-deprived exhibiting the symptoms related to being drunk on alcohol. When it comes to your ability to react to certain situations quickly, proper sleep is vital.

You may have your doubts about this comparison, but according to the Centers for Disease Control and Prevention, being awake for 24 hours straight is comparable to having a blood alcohol content of 0.10% – a level higher than the legal driving limit. You may not be routinely staying up 24 hours straight, but if you’re repeatedly getting five to six hours of sleep every night (or if your child is often staying up late), your athletic ability may be impaired, and you will begin to feel increasingly impaired.

Steps to Improve

The simple act of resting for eight hours every night has the power to improve your overall health and wellness in ways you might not believe. It’s time to stop neglecting sleep and instead take advantage of its healing properties to live your healthiest, most productive daily life. If you struggle to get the recommended seven to nine hours of sleep every night, it’s time to switch up your routine and try some new techniques for rest. Consider the following for your new sleep lifestyle:

Avoid Caffeine

The smell of freshly brewed coffee first thing in the morning is invigorating and a welcome start to the day. The problem with coffee, however, is that people rarely limit it to the morning. Often, the cups will continue to flow throughout the day as energy levels dip. The caffeine found in coffee is a strong stimulant and most people aren’t aware of how long it actually stays in their system. Caffeine can remain active in your body for 10 to 14 hours. This means if you drink a cup of coffee at 4 p.m. to help you finish a final report, the caffeine won’t dissipate from your system until at least 2 a.m.! If you’re looking for a better night of sleep, start by cutting off your caffeine intake before noon to allow your body to transition naturally to the rest and sleep states of the day.

Remember, avoiding caffeine doesn’t just include coffee! Any caffeine source counts. Energy drinks, certain teas, and soda should all be avoided to limit your caffeine consumption late in the day.

Create The Right Sleep Environment

If you really want to revamp your sleep routine, it’s time to take distractions out of the bedroom. Start by removing the TV, as well as other gadgets that may be capturing your attention at night when you’re trying to fall asleep.

While you are at it, this also a great time to get a new mattress or pillow if you’ve been noticing any neck or back pain after you get up in the morning. Having a comfortable place to rest makes it a lot easier to fall asleep, and you’ll look forward to bedtime more if you know your mattress isn’t going to be squeaking with each movement. You will wake up refreshed and ready for a new day with these small steps in the right direction.

Exposure to the Correct CCT at the Correct time.

As we read above, sunlight exposure is very important for regulating your sleep patterns. You should be getting, at the very minimum, 30 minutes of sunlight exposure each day. Consider getting outside more if you’ve been sleeping poorly.

Admittedly, sunlight exposure is not always possible. You may work in a school or office building that doesn’t have many windows that let in natural light, or your work schedule may have you up at night and sleeping during the day.

In these cases, it can be helpful to look into a hue-correcting light that mimics the natural wavelength of sunlight for you! Using this kind of artificial light can help keep your circadian rhythms on schedule by creating the sun’s day-night cycle – even if you’re not getting outside in the sun as often as you like.

Sound impossible? Not anymore. The team at LEDdynamics has created a product that is perfect for people who regularly find themselves inside all day. The PERFEKTLIGHT technology, recently recognized by the IES, replicates the changes in light temperature and intensity as the sun travels across the sky. LEDdynamics has also managed to perfect the coloring tuning between two color temperatures. Often, when you tune between two colors you end up with a visible hue error, which can be distracting for people sensitive to light differences.  With PERFEKTLIGHT, you don’t have to worry about a hue error. Instead, you can reap the circadian sleep benefits that come with using a lighting fixture that mimics the sun!

If you are suffering from any amount of circadian rhythm-related sleep disorders, or simply want to experience the benefits of living your daily life with the natural cycle of light, its time to bring the PERFEKTLIGHT into your world! With PERFEKTLIGHT, you can ditch your sleep-disrupting artificial light and reclaim the energy and sleep your body is hungry for.

Click the following link for an in-depth article on PERFEKTLIGHT, or contact us now.