The internal systems that regulate our virtually perpetual cycles of sleep and wakefulness make up an amazing mechanism. However, there are a number of both internal and external factors that can dramatically impact the equilibrium of your sleep-wake cycle.
Light is one of the major extrinsic factors that have a deep impact on the quality of sleep. Light exposure early during the daytime excites the mind and body, promoting feelings of alertness, energy, and thus wakefulness. However, the same light that stimulates alertness at nighttime can seriously pose a problem for a refreshing, healthy, and plentiful sleep. In the evenings, exposure to light can make it harder for one to fall asleep. Inadequate darkness can result in prolonged and frequent awakenings.
Pitch black darkness is essential for the body to fall asleep. In absence of light, the brain sends a signal to the body indicating that it is time to rest. When there is a light source present at the wrong time, the body’s circadian rhythm, a biological mechanism that regulates sleep-wake cycles, can be adversely affected, thereby disrupting both the quantity and quality of sleep.
Our brain produces a hormone called melatonin, which basically sends our body a ‘time to sleep’ signal after which the physiological groundwork for the sleep-cycle to take place. This includes feeling lethargic, muscle relaxation, and a drop in body temperature. When darkness starts to fall after sundown, the levels of melatonin automatically increase and continue to do so throughout most part of the night, peaking around 3:00 am.
However, when the sun starts to rise, our melatonin levels start to drop and remain low throughout the day. Exposure to light during nighttime can mess up the naturally programmed increase of melatonin levels, which slows down the body’s natural progression to sleep.
In addition to regulating our melatonin levels, sleeping in complete darkness helps lower the risk of depression. Studies suggest that a healthy sleep cycle is integral to maintaining a balanced mental and emotional well-being. If your quality of sleep gets affected due to even a bit of light, then you run the risk of having sleeping issues, which are well-known for causing a range of emotional problems, including depression.
Lastly, pitch black darkness is essential for quality sleep since it helps lower the possibility of a metabolic disorder. A study published in 2014 in The Journal of Clinical Endocrinology and Metabolism explained that living out of sync with the rising and setting of the sun can lead to various health issues.
So-called “night owls” were seen to be more vulnerable to having muscle loss, diabetes and metabolic syndrome, as opposed to who went to bed and woke up at times in accordance with the dark cycle and day’s light, in spite of getting the same quantity of sleep.