What Makes you Sleep? - Adenosine and Melatonin (3)

Which Two Substances Affect Your Sleep?

While you may try to sacrifice sleep to squeeze more activities into your day, eventually the desire for deep rest will become impossible to ignore. This desire stems, in part, from two key substances produced in your body. The first is adenosine, which is a substance that gradually accumulates in your blood while you’re awake. When you fall asleep, your body begins to break down this adenosine. It is the accumulation of adenosine, along with numerous other complicating factors, that makes up the “sleep debt” after a few sleepless nights. This debt may cause you to sleep longer than usual, or inadvertently nap during the day. Your body’s mechanisms cannot adapt to sleeping less than it naturally needs. Chronic sleep deprivation can eventually overwhelm you.

The other substance is melatonin, a hormone that promotes sleep. As the night falls, the release of melatonin makes you naturally feel sleepy. It’s part of your internal “biological clock” that governs how tired you feel and your sleep patterns. This biological clock is located in a small cluster of cells in the brain and runs day and night. Internal and external environmental cues, such as light signals received through your eyes, control these cells. When the body clock triggers the release of melatonin, the brain and body begin to prepare for sleep. As melatonin is released, you’ll feel increasingly drowsy.

Because of your biological clock, you naturally feel the most tired between midnight and 7 a.m. You also may feel mildly sleepy in the afternoon between 1 p.m. and 4 p.m. when another increase in melatonin occurs in your body. This regulatory role of the biological clock allows you to naturally sense the best time to fall asleep. This slight lethargy during the day seems to be a small reminder from nature to remind us to slow down and take a break.

The Impact of Society’s Non-Stop Nature

Your body clock exquisitely regulates your daily alertness, keeping you at your best during daylight and at your lowest in the early morning. Consequently, most people are most productive during the day. However, in our round-the-clock society, working at night has become a last resort for some. Alarmingly, nearly a quarter of workers work outside of the day, and of those, more than two-thirds suffer from sleepiness and/or sleep disorders. Night shift fatigue not only affects productivity but also may bring safety risks. Some of history’s major industrial disasters, such as the Three Mile Island and Chernobyl nuclear power plant accidents and the Exxon-Valdez oil spill – have been caused, in part, by mistakes made by overly tired workers on the night shift or an extended shift.

A recent study has revealed the shocking fact that one-fifth of night shift workers had a car crash or a near miss in the past year while driving home from work because they are so tired. This is just one of the many pitfalls of night shift work. Night shift workers not only take great risks in terms of traffic safety, they also face a number of physical problems, including heart disease, indigestion, fertility problems and emotional disorders. A large part of these health problems may be related to their chronic sleepiness, a phenomenon that often stems from a mismatch between the body clock and the actual sleep schedule.

The Role of Cytokines in Sleep Regulation

In addition, many factors affect your need for sleep, one of which is the hormones secreted by the immune system called cytokines. When fighting certain infections or chronic inflammation, the amount of cytokines secreted increases, which may prompt you to sleep more than usual. The extra sleep helps you to store the energy needed to fight off infection. New research shows that getting enough sleep can significantly improve the body’s ability to cope with infection.

Balancing Work Schedules with Natural Biological Rhythms

People are creatures of habit, and one of the hardest habits to break is the natural wake and sleep cycle. Together, a number of physiological factors help you sleep and wake up at the same time each day.

In the following articles, we will delve into how night shift work affects our body clock and how to maintain healthy sleep habits in the fast-paced modern life. Let’s unravel the mystery of sleep and explore the hidden factors that influence our late-night dreams.

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