The Science Behind Why We Sleep—Adenosine and Melatonin

Author:
Margaret Perrottet
Updated:
Sep 9, 2023 12:18 PM EDT

Why Do We Sleep?

We spend one-third of our lives sleeping. Without sleep, we don't feel well. Research is making it clear that lack of sleep is linked to many health risks. It is as important to our well-being as nutrition and exercise.

We may get tired at different times of the day. Some of us fall asleep early in the evening, some late at night, and insomniacs struggle to get to sleep at all - but eventually, we all fall asleep. What is the secret of how we slip into this essential state? Scientists have found that two important cycles regulate our sleep—the homeostatic sleep drive and the circadian signal. These cycles are controlled by two vital components—adenosine and melatonin.

There are many forces at work behind our sleep cycle

The Homeostatic Sleep Drive Process

The homeostatic sleep drive process regulates the drive to sleep based on the amount of time we're awake and how much energy we're expending. The chemical adenosine binds to adenosine receptors during waking hours. The more you do and the longer you're awake, the more adenosine you accumulate, making you feel tired. It's your body's way of saying you've done enough, and it's time to quit. While you sleep, this chemical is broken down and adenosine levels decrease. Therefore, scientists feel that adenosine is the way the body keeps track of how much sleep you've gotten, and how much sleep you need. If you don't get enough sleep, the adenosine in your body is still remaining when you wake up, making you feel groggy. The next night you may sleep longer to rid your body of the extra accumulation of adenosine.

The Circadian Process

The circadian process is regulated by a tiny internal biological clock located in the hypothalamus called the suprachiasmatic nucleus (SCN). This structure receives light waves from the eye directly through the optic nerve. This Light resets the clock to correspond to the day-night cycle. Signals from the SCN travel to the pineal gland which switches off the production of melatonin during the day, and increases it during the night. Similar to adenosine, the build-up of melatonin in our bodies makes us feel sleepy. This is why Melatonin is often taken as a natural sleep aid and is successful for many people.

It All Comes Together

This combination of melatonin from the circadian system and adenosine from the homeostatic system normally peaks together around 9 P.M. signaling the body that it's time to sleep. If everything is working as nature intended, we drift off peacefully to a good night's sleep shortly thereafter.

Pleasant dreams!

Why Does Caffeine Keep You Awake?

Caffeine is a substance that can block the adenosine receptors in our bodies, thereby interfering with the accumulation of adenosine. Because you have less adenosine built up in your system, you feel energized and less fatigued.

Turn off Electronic Devices in the Bedroom!

Did you know that having a light on in the bedroom interferes with your sleep? Scientists are even concerned about the light emitted from our electronic devices such as smartphones, laptops, tablets, and E-readers. They feel that light in the bedroom can completely distort your natural sleep cycle. Why? Because light interferes with your body's ability to produce melatonin. Scientists recommend that if you want a good night's sleep, turn off those electronic gadgets in your bedroom before retiring for the night!

Lack of Sleep Puts You at Risk for...

Heart attack
Heart failure
Irregular heartbeat
High blood pressure
Stroke
Diabetes

Having Trouble Sleeping? Try These Tips!

References

Adenosine & Sleep | LIVESTRONG.COM
Adenosine & Sleep. Adenosine is a chemical in your brain and body that belongs to a class of substances called neurotransmitters. These substances support basic nervous system communication by carrying messages across the gaps between individual

Questions & Answers

Question: How does missing stage four in a sleep cycle affect my mind and body?

Answer: Since the stage four (deep sleep) cycle is very important for the restoration of the brain and body, you certainly could be feeling some ill effects from missing out on this important cycle. Try out some of the tips in the article for a good night's sleep.

Comments

Margaret Perrottet (author) from San Antonio, FL on June 07, 2013:

From what I've read, it's difficult to get a good sleep in four hours. My husband worked night shift for years, and would sleep from 8:00PM to 12 midnight, go to work, then sleep again from 12:00 PM to 4:00. I don't think he ever felt truly rested with that sleep cycle. My guess is that it probably stops you from getting into a really deep sleep, but I'd have to research it. Thanks so much for stopping by and asking an interesting questions, Easy Exercise.

Kelly A Burnett from United States on December 27, 2012:

Can some people really train themsselves to sleep only 4 hours and still be healthy? If they do, will they still have two types of sleep?

Margaret Perrottet (author) from San Antonio, FL on December 21, 2012:

Thanks so much for reading and taking the time to comment, Annamie. Glad you found this article useful.

Annamie Cureteyz on December 21, 2012:

And now I know! This is such a very informative post, I honestly don’t have any idea about things and issues concerning sleep but now I know!! Thank you for sharing this, keep posting!

Margaret Perrottet (author) from San Antonio, FL on October 21, 2012:

Thanks BlissfulWriter - I enjoy yours as well!