Here are some reasons why sleeping in total darkness provides the best sleep:
- Melatonin Production. Melatonin is a hormone that regulates our sleep-wake cycles and is produced at night and best produced during total darkness.
- Key Melatonin Functions. Melatonin helps lowers blood pressure, glucose levels, and body temperature — key physiological responses responsible for restful sleep.
- Cancer Prevention. The hormone and biochemical disruption from lack of good sleep is a risk factor for cancer. Scientists aren’t entirely sure why, but studies consistently show a correlation between lack of sleep and cancer. By way of example, people living in areas with the most artificial light at night had a 27 percent higher risk of developing pancreatic cancer compared with those in the least-lit areas. See AACR: Light at Night and Risk of Pancreatic Cancer in the NIH-AARP Diet and Health Study
- Lowers Diabetes and Obesity Risks. Dark sleep produces the most optimal levels of melatonin and provides the framework for glucose regulation. A single night of light exposure is unlikely to cause significant harm, However, consistent low-level light exposure over time can gradually interfere with the body’s functioning, See ScienceDirect Sleep Medicine: Bedroom lighting environment and incident diabetes mellitus
- Mental Health and Stress Management. Sleeping in darkness helps improve mental health and stress management.
- Blue Light Interference. Light from laptops, tablets, smartphones, and energy-efficient light bulbs interfere with melatonin production and deep sleep. Blue light from light-emitting diodes (LEDs) is good at suppressing melatonin production. See Royal Society Publishing: Human melanopsin forms a pigment maximally sensitive to blue light
The Darker the better
A dark sleep environment helps you reach deeper, uninterrupted stages of sleep, which are essential for sharp thinking, creativity, emotional control, and even decision-making. The darker the better the sleep. See Gizmodo: Why We Need To Sleep In Total Darkness
The Yin and Yang of darkness and sunlight
In Chinese philosophy, yin and yang is the concept of opposite cosmic principles or forces that interact, interconnect, and perpetuate each other. “Yin” is retractive, passive and contractive in nature and is associated with qualities such as darkness, femininity and absorption, while “Yang” is repelling, active and expansive in principle, and represents light, masculinity and penetration. This dichotomy in some form, is seen in all things in nature—patterns of change and difference.
Melatonin is produced by the brain’s pineal gland at night as there’s no optic signal to the Suprachiasmatic Nucleus (SCN), the small region of the brain in the hypothalamus, situated directly above the optic chiasm. These cells respond to light and dark signals and are responsible for regulating sleep in animals. The optic nerves in our eyes senses light and transmits a signal to the SCN telling the brain that it’s time to wake up. It also kickstarts the process of (i) raising body temperature and (ii) producing hormones like cortisol. Our cortisol levels are relatively low at night and higher during the day, allowing for the stabilization of energy levels.
The Yin and Yang: Importantly, our melatonin levels are influenced by the amount of exposure we had to light during the previous day.
The bottom line for the best sleep: Get outside in the sun during the day. Sleep in darkness at night.
See 8 Natural Ways to Boost Melatonin for Better Sleep. See also Sleep, Rest and Recovery: Tips to Natural Good Sleep.
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