The miracle of Circadian Rhythms

One of the most dramatic features of the world in which we live, is the cycle of the day and night. Almost all species exhibit daily changes in their behaviors and physiology in response to this cycle. These daily rhythms are not simply a response to the 24-hour changes in the physical environment, imposed by the earth turning on its axis. Instead, they arise from a timekeeping system within the organism. This timekeeping system is essentially a ‘biological clock’. It allows the organism to anticipate and prepare for the changes in the physical environment that are associated with day and night.

The term ‘circadian’ from ‘circadian rhythm’ comes from two Latin terms, “’circa’ (meaning ‘around’), and ‘diem’ (meaning ‘day’). Put together, the word means ‘a naturally recurring 24-hour cycle. Circadian rhythm is present in the sleeping and feeding patterns of animals and humans. It regulates body temperature, brainwave activity, hormone production, cell regulation and other biological activities.

Our circadian rhythm is a cycle of about 24 hours, that is linked to the rising and setting of the sun. Deep in our brains, a tiny, powerful cluster of nerve cells called the suprachiasmatic nucleus (SCN) works 24/7 as our internal clock. It programs key activities such as cell regeneration, detoxification, patterns of brain activity and production of hormones. These changes, in turn, regulate the sleep-wake cycle. When it gets dark, your SCN begins to lower body temperature and also signals the release of melatonin, a hormone that makes you sleepy. But exposure to natural or artificial light at night (television, computers, phones, Xbox, etc.) completely changes the picture. The light triggers an increase in body temperature, along with the release of wake-up hormones, such as cortisol. Light exposure also inhibits melatonin production. Because these internal pathways are so sensitive to light and darkness, it is easy for them to be thrown off. That’s why simply switching on the lights for a few seconds can shift your circadian rhythm by more than 40 minutes!

A Circadian Rhythm In Flow

The following table summarizes a few of the changes that occur in a person who rises early, eats lunch around noon and sleeps through the night.

Time [RC1]	Event within the body
4:30	Lowest body temperature
6:45	Sharpest rise in blood pressure
7:30	Melatonin production stops
8:30	Bowel movement likely
9:00	Highest testosterone production
10:00	High alertness
14:30	Best coordination
15:30	Fastest reaction time
17:00	Greatest cardiovascular efficiency and muscle strength
18:30	Highest blood pressure
19:00	Highest body temperature
21:00	Melatonin secretion starts
22:30	Bowel movements suppressed
2:00	Deepest sleep

At least, this is what it should be.

The Importance of Quality of Sleep

So far, we have mainly examined the effect of alcohol on sleep quantity. But that’s not all the bad news. Sleep is not just shutting your eyes and opening them again 8 hours later. Sleep is a miracle of rejuvenation. This process is highly dependent on the right mixture of the two major sleep types—REM (rapid eye movement) sleep and non-REM sleep (light and deep).

Deep sleep is where the healing happens. The main task of the body is repair. Blood flow is directed away from the brain while the pituitary gland shoots out growth hormone. This little miracle molecule is responsible for muscle repairs and tissue growth—exactly what you need after a good workout.

But your brain needs to repair itself just as much. The brain needs to deal with information it has received during the day and make sense of it. We are talking about dreaming—that is where the REM sleep comes in. You may think of REM sleep as the equivalent of a dog chasing a rabbit in his dreams. His legs are going nuts, and he is making woofing noises, yet he is well asleep. REM sleep is the opposite for us. The only things that move in the body are the eyes, the breathing muscles, and the diaphragm. The rest of the body is remarkably still. But it’s inside where the changes are happening. Imagine the picture of an active brain in a paralyzed body. Body temperature, heart rate and blood pressure increase in line with a strong activation of the sympathetic nervous system—the ‘fight or flight’ response. In REM sleep, the brain gets rid of information it no longer deems relevant. Put differently, REM sleep helps with learning and memory. Your body needs this sleep to retain information, which explains why students trying to learn all night before an exam do worse than those who get some sleep.

‘Sleep architecture’ refers to the picture of the skyline of a large city. If you imagine a graph where awake or REM sleep is highest and deep sleep lowest, you will get an up-down-up-down picture throughout the night. In a young adult, you would normally see four or five alternating non-REM and REM periods. Most deep sleep occurs in the first half of the night. As the night progresses, periods of REM sleep get longer and alternate with deep sleep. The older we get, the less sleep we experience and the more time we wake up. Hmmm… getting old is clearly not for the faint-hearted!

Take Action To Get Deep And Regular Sleep

• Learn everything you can get your fingers on about sleep and insomnia.
• Keep a sleep diary for two weeks. Start by writing down when you go to bed, and in the morning, add the estimated time you fell asleep. Write down how you felt if you couldn’t sleep and what you did to get to sleep. When did you wake up in the morning? If you woke during the night, how many times did it happen, and how did you feel in the morning?
• Look through your medications. Are there any that can potentially cause insomnia (or make it worse)? Next time you’re with your GP, ask him that question. Be aware of over-the-counter medications such as cold medications. They often contain pseudoephedrine or other medications that are good for a cold but might keep you awake.
• Learn sleep hygiene. It is time to create the best sleeping habits you can possibly think about. This means that you have to redesign your schedule. From now on, go to bed at roughly the same time in the evening and wake up roughly the same time every morning.
• Limit your caffeine intake. That does not mean you have to be completely abstinent. Rather, give yourself a cut-off time, for example, 3 o’clock in the afternoon. Make a contract with yourself that you will not have coffee or other caffeine-containing liquids after that.
• There is a time and place for many words, and there is also a time and place for sleep (paraphrased from Homer). Unless you live in a one-bedroom apartment, make your bedroom a place for sleep only. Remove the work, television, computer, and anything else that could keep you awake.
• Pleasure yourself. What you need is a regular and soothing bedtime routine. Could that include a nice long walk in the evening? Maybe a warm drink, such as hot chocolate or chamomile tea? A series of relaxation exercises or yoga? Maybe take the recommendation literally—an orgasm is a beautiful thing to finish off the day.
• Adjust your expectations. In our modern-day society we expect instant gratification and everything else to be just perfect. When it comes to sleep, this is not necessarily the norm. About 1 in 10 nights will be rubbish. If you cannot sleep and you wake up during the night, do not get up. Do not try to be the hero and clean up the garage or otherwise be productive. It is what it is. If that happens, what can you do? Just lie there until you fall asleep again (or until the sun tells you to get out of bed).
• Keep the lights off. Do some relaxation exercises in the dark. Even a short period of light (for example going to the toilet and switching on all lights) leads to an activation of your brain for the next 30 to 40 minutes.
• Talk to your GP. Sometimes our sleep is interrupted by a real medical problem, such as snoring or the frequent need to pass water. In such cases, seek help from your GP. Heavy snoring and short periods in which you do not breathe are signs of moderate to severe obstructive sleep apnea. This is an insidious medical emergency for which you should be checked out and treated. The same holds true as far as frequent passing of water is concerned. If you have drunken 2L of water in the evening, it is probably normal that you have to get up once or twice in the night. However, if you frequently need visit the toilet, sleep half upright with the help of several pillows, have swollen legs or an increasing tummy girth, it is high time to say hello to your GP. What you are experiencing might be that your heart is not working as strong as it should. Having to go to the toilet several times at night is part and parcel of this problem. Get yourself checked out.
• Talk to your partner. It might not be you who is snoring, but rather your partner. Or your partner might have a different work schedule from you, and this is certainly not helping you to go to sleep or stay asleep. Time for some serious negotiations! Who is sleeping where? How can you protect your sleep in the best possible way?
• Don’t nap and whatever you do, do not fall asleep in front of the television. Your body requires darkness, peace and quiet for you to sleep. Treat yourself to the best possible circumstances. And look forward to a good night’s rest.

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