The Chemistry of Sleep

Sleep is a necessary routine in our life, similar to food and water, to keep our body healthy, and recharging of our brains to keep and prepared for a fresh day. Enough sleep is essential to keep the brain active, which is critical in concentration, learning, and memory storage. Researchers revealed that sleep deprivation not only makes us cranky and irritable but also imparts health burdens like blood pressure, cardiovascular disease, depression, and obesity. Evidently, sleep follows circadian rhythms and homeostasis mechanisms. The controlled time of sleeping and waking up without an alarm is due to circadian rhythms followed by the synchronization of the body with the external factors such as light, temperature and many others, and even continue in the absence of these factors. Human body is reminded to sleep at a certain time by sleep-wake homeostasis. As the sleep deprivation period increases, which results in a longer and deeper sleep.  

Its interesting to have a thought about the chemistry behind sleep! Well, not everyone knows that numerous chemicals are involved throughout the sleep and wake cycle. Melatonin and adenosine, are the two most crucial molecules released in the body, which plays a pivotal role in sleep regulation. As a result of various activities, the human body burns a lot of energy, which results in the production of adenosine.  The activity of neurons is suppressed by the binding of the adenosine to the adenosine receptors embedded in neurons or nerve cells and makes us feel drowsy. The feeling of exhaustion caused by the creation of adenosine makes you sleepy as the day ends, and incomplete sleep results in tiredness. Notably, the ideal sleep burns off all the created adenosine.

The pineal gland produces melatonin when the retina is not exposed to light. The darkness inhibits the signal transfer from the suprachiasmatic nucleus (an area of the brain), which in turn causes melatonin production by the pineal gland. The melatonin is derived from tryptophan through multistep process with the aid of various enzymes. Among, one of the key enzyme is serotonin-N-acetyltransferase (SNAT), and its activity decides the melatonin production. The signal transferred by the exposure to light to the pineal gland from retina passes through the suprachiasmatic nucleus results in degradation of SNAT. Whereas, it gets phosphorylated at night and thus increases the melatonin, which is why we tend to wake up in the morning. Well, from now on, if someone stops you from sleeping, tell them you have too much adenosine left to burn off !

Written by: Supriya Jain, DST-JRF, Yenepoya Research Centre, Yenepoya (Deemed to be University), Mangalore-575018, Karnataka, India.

Her profile: https://yenepoya.res.in/team/supriya-jain/#1561549713017-7925d3bc-4beb

Artwork: Supriya Jain

Edited by: Dr. Renjith Johnson and Saketh Kapoor