Sleep is one of the most important physiological functions for humans. Sleeping allows us to repair our tissue, grow our muscles, solidify and consolidate our memories and enables neuron survival. To do all this, our sleep must be the most efficient it can be. One hormone takes the lead in this situation: melatonin !
For our scientific readers and for those who aren’t, here are a few facts on melatonin…
WHAT REALLY IS MELATONIN ?
Derived from serotonin, a neurotransmitter in the central nervous system (CNS), melatonin is an endogenous hormone, meaning that it is produced by the body.
BUT WHERE IS IT SYNTHESIZED AND RELEASED ?
Melatonin is produced by the pineal gland, situated in the middle of the brain and regulated by the hypothalamus. It has been proved that the pineal gland is a major transducer of photoperiodic information which are reactions of the organism to the length of day or night. This means that the production of melatonin is, partially, a response to light exposure. In fact, the biosynthesis of melatonin occurs mainly during the night or under dark light conditions and lasts around ten hours. Light, natural or artificial, is actually able to activate or inhibit melatonin production. Once melatonin is secreted, it is released straight into the bloodstream.
The production of melatonin is the highest between 3 and 6 years old, and reaches only 80% of its potential during adulthood. A calcification of the pineal gland due to aging is also responsible for decreasing its secretion, hence the more you age, the more you find it difficult to sleep.
WHAT ARE THE DIFFERENT FUNCTIONS OF MELATONIN ?
The main function of melatonin is to communicate information regarding the daily cycle of light and darkness to different body structures. Also known as the sleep hormone, it is the key to regulate our chrono-biological rhythms as it synchronizes, strengthens and maintains our circadian rhythms.
It has also been proved that melatonin helps improve the onset, duration and quality of sleep. Consequently, melatonin also plays a part in neuronal survival.
Lastly, melatonin plays a role in adjusting our core temperature and our sleep-wake rhythms, allowing the organism to adapt itself according to its environment.
HOW CAN OUR ENVIRONMMENT INFLUENCE THE PRODUCTION OF MELATONIN ?
Multiple researches have been made on the circadian rhythm of core temperature, demonstrating that our body temperature follows a periodic phenomenon: it reaches a maximum during the day, a minimum during the night and keeps following this cycle. This core temperature rhythm has been used as a marker for circadian rhythms in human beings.
But how does melatonin fits in all of that? Well, experiments have shown that suppressing the natural rise of melatonin during the night attenuates the nocturnal decline in core temperature which helps fall asleep faster and easier. In the same study, other experiments showed that administration of melatonin during the day caused a significant drop in core temperature, leading to sleepiness.
This is where MOONA becomes your best friend. MOONA is a smart cooling device, that helps you control your body temperature. How ? By cooling your head/neck area, allowing your core temperature to decrease as well and helping the secretion of melatonin and inducing sleep. To wake you up, MOONA will slowly increase its temperature, allowing you to wake-up naturally. And because each individual has his own preferences, you can change your temperature profile at any time on the MOONA app, and MOONA will remember it, providing you a tailored experience each night.
Exposure to light at night is deleterious to health. How is this possible? Being exposed to too much light can inhibit the production of melatonin which, to an extent, can lead to sleep deprivation and a disruption of our circadian system. This is why night work can be hard, as you’re working when you should be sleeping, so the time spent sleeping is decreased and your circadian rhythm structure is disrupted.
How does light affects the production of melatonin?
When the retina senses a decrease in light, a neuronal message is transmitted by the central nervous system (CNS) to the suprachiasmatic nucleus, our internal clock, and a cascade of reactions activates the production of melatonin. Once melatonin is produced, it will transmit the photoperiodic information to every structure in the body that has the specific receptors.
On the other side, light decreases the secretion of melatonin when several conditions are met: extended exposure to light at an optimum time, between 2 and 4am. Note that blue lights (lights from phones, computers or any screen) have the worst effect on the secretion of melatonin.