Understanding the Light-Dark-Cycle — 4 Tricks to Hack Your Sleep

Science-based content to increase your performance

Light and Darkness

After reading this article, you’ll have understood how light and darkness influences your sleep and how to leverage that knowledge to fall asleep faster and sleep healthier. You’ll also have learned what the difference between artificial and natural light settings is — and why this difference is relevant for you.We’ll explain how you can improve sleep quality and daily productivity significantly by:

  1. Applying blue light to boost concentration for specific activities
  2. Dimming lights one hour before you go to bed
  3. Leveraging vitamin D3 to sleep better and feel more alert

The light-dark-cycle

Figure 1: Sleep cycles for different probands; Source: https://www.trilux.com/de/beleuchtungspraxis/innenraumbeleuchtung/allgemeine-anforderungen/licht-und-nicht-visuelle-wirkungen/der-circadiane-rhythmus-und-die-innere-uhr/

Disturbing Your Light-Dark-Cycle Has Severe Consequences

Hence, yes, rhythm is important. Effects reach much farer than mere discomfort and fatigue. Especially shift workers, those suffering most from disturbances in light-dark-cycles, report higher risk of heart attacks and higher risk of cancer of about 15%. [3] Sustained night work was furthermore linked to 50–100% higher risks of breast cancer for nurses and many other diseases such as diabetes, cardiovascular risks, obesity, mood disorders and age-related macular degeneration. [4][5]

Natural vs Artificial Light

Vitamin D3 and Food

First of all, while many believe that we could eat food containing enough vitamin D3, the truth is a little bit more complicated. To reach a minimum level, we would have to drink about 22 liters of milk and eat about 5 kilograms of fish — every day. Considering the fact that our stomach would simply explode from trying this, let us have a look at a valid alternative: naturally secreting vitamin D3 by exposure to sun light.

Facts About Vitamin D3 Secretion

How much sunlight a day do we need? What happens if we spent some days completely deprived from sun? How do we secrete vitamin D3? Let us list the most important facts about vitamin D3 below:

  • Vitamin D3 can only be secreted if sunlight is strong enough. North of the latitude of Barcelona (approximately 42nd), vitamin D3 can only be secreted during summer. We can use our shadow to test whether vitamin D3 secretion is possible: If our shadow is as long as us or even longer, vitamin D3 secretion is not possible. [8]
  • Vitamin D3 is stored in our body up to 6 months. We can thus ‘charge’ up in the summer to ‘save’ for the winter. [8]
  • Vitamin D3 has significant influence on our inner clock and can be a fantastic means of inhibiting jet-lag. [9]
  • Vitamin D3 inhibits melatonin secretion. [10]
*All of those numbers are merely benchmarks and vary based on age, skin type and time of the day.


[1] Zawilska, J.B. (1996). Melatonin as a chemical indicator of environmental light-dark cycle. Acta Neurobiologiae Esperimentalis, 56, 757–767. Retrieved from https://pdfs.semanticscholar.org/7950/a37963605cdd7c3c8c97dc0dc6c201bffe8b.pdf

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