Why we need Lumos?

Every day, we wake up, dress in a dimly lit room, duck inside the comfort of our vehicles for the morning commute, and type away in front of a screen for the rest of the day. We are part of the indoor generation. On average, people spend 90% of their day indoors. However, the comfort and convenience we gain from staying indoors come at a cost.

Our biological clock relies on the natural light-dark cycle to reset our circadian rhythm every day.

The lack of exposure to natural sunlight, amongst other reasons, leads humans to develop circadian rhythm disorders which include:

Difficulty falling asleep

Waking up several times

Waking up too early

These disturbed rhythmic sleep patterns result in symptoms like insomnia, excessive daytime sleepiness, difficulty waking up in the morning, depression, the stress in relationships, poor work/school performance and an inability to meet social obligations.

The Center for Disease Control and Prevention reports that up to 35% of adults (>18) report having less than 7 hours of sleep. The same report also states that adults who sleep less than 7 hours are more likely to be obese, physically inactive and are prone to chronic health conditions like heart attacks, asthma, arthritis, depression and diabetes to name a few. However, the impact is more than just medical, it’s economical.

A 2016 RAND report estimated that employees sleeping fewer than seven hours per night cost the US more than $400bn a year, and the UK $40bn a year.

These problems are not just limited to adults. Adolescents need 8 to 10 hours of sleep per night. But, more than two-thirds of US high school students report getting less than 8 hours of sleep on school nights. The trends suggest that students in higher grades are more susceptible to sleep shortage compared to their younger counterparts.

It could be said that we are all a part of a silent sleep disorder epidemic and must work on increasing awareness and developing solutions that help our societies at large.

The science behind it all

Your circadian rhythm is like an internal clock with a period of approximately 24 hours. It is entrainable meaning your circadian rhythm can be coupled to a zeitgeber (oscillation forces). When we have relatively consistent timed zeitgebers it can support stable entrainment. For example, when we consistently receive high light exposure during the day, and minimal light at night. Ideally, we want the internal period (circadian rhythm) to be synchronized with the external period (light/dark cycle).

The 24-hour light/dark cycle is the primary zeitgeber for humans and when they are synchronized, we are able to initiate biological processes to help us function optimally.

When we sense bright light as opposed to soft and warm light, our bodies release different hormones.

Cortisol levels increase when we sense more light, and we become more alert

Melatonin is released when we see less light, to make us more tired

Sunlight ranges between 50,000 and 100,000 lux, much higher than the average indoor light bulb of 250 to 500 lux.

The graph below demonstrates the light exposure we typically experience, especially during the winter. As you can see we are mostly under-exposed to light during the day (except for times we either step out for a walk or drive in a car) and over-exposed at the night.

The human circadian system can be shifted based on the level of light intensity. “Phase shift” demonstrates how much your circadian rhythm can move in just one night. When we are outdoors on a sunny day, our bodies can shift the circadian rhythm by up to 3 hours. This is how your body adjusts in different time zones.

The way our bodies receive light is through the eyes. Our eyes have three known types of cells: rods, cones, and discovered about 20 years ago, the intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells express a photopigment called melanopsin which allows these cells to respond to light and the ability to assess changes in ambient light levels. When melanopsin cells are exposed to light, in particular blue light, it stimulates the SCN which is where your circadian rhythm is located, therefore playing a big role in circadian rhythm entrainment.

The most sensitive type of cell to blue light are ipRGCs, therefore when we see blue light, it might not seem very bright, but it can have a powerful effect on your biology.