What Is Your Circadian Cycle?

Rhythms of the body
There are very few things in nature that are linear, everything moves in circles of changing and adapting life patterns. As humans we have natural body and brain cycles that run over a 24 hour period.
These cycles or rhythms control many body functions switching them on or off at the most appropriate times. For example the circadian rhythms are responsible for or have an influence over:
- Feeling hungry
- Body temperature
- Sleep-wake-sleep patterns
- Hormone production
- Cell regeneration
These rhythms are found not just in humans but in other animals, plants,fungi and even some bacteria. Scientists have found that these rhythms are *endogenously generated, but there are environmental factors that also have an influence - such as how much day light there is and seasonal temperatures.
*Endogenously means that the body produces these rhythms from within.
Biological Clocks.
Within the cells of our body, there are certain molecules that are responsible for driving the circadian cycles. They are in turn controlled by one master biological clock that is found in the brain. The hypothalamus has an area within it called the SCN (suprachiasmatic nucleus). There are about 20,000 nerve cells within the SCN and lying just above our optic nerve in the eye. This proximity to the the nerve of vision is able to relate immediate information on how light or dark the environment is. In addition, our personal circadian rhythms are determined genetically by how our mother and father's cycles operate.
One of the main functions of the circadian cycle is to regulate our sleep-awake-sleep patterns. So much so that any interruption of the rhythm can have unpleasant side effects - this is why we experience jet lag. However, many people also suffer from sleep disorders that are thought to be wholly or partially influenced by factors affecting the circadian cycle.
Circadian cycle and sleep
The body's master biological clock that we mentioned earlier - SCN (suprachiasmic nucleus) controls the release of a substance called melatonin. Melatonin is a hormone secreted by the pineal gland in the brain - and it's this hormone that makes you feel sleepy at night time. Medical researchers have found that as we get older, less melatonin is released. This is probably one reason young people usually don't have any problems sleeping as they will have higher amounts of melatonin secreted.
Babies don't have a functional circadian cycle until about 12-16 weeks - this is why they can seem to turn night into day. New born babies for example don't develop their light-dark cycles until about 6 weeks old. However, even at 12-16 weeks, babies are still developing their rhythms - they will only slowly mature into longer sleeping patterns at night.
Jet lag
In the case of jet leg what happens here is that although you travel through different time zones, your circadian cycle is set to your home environment. Your watch might say 9am, but your circadian rhythms are still in a home cycle where it might be 9pm. Eventually your circadian rhythms will come back into tune but it can take a few days. How severe you experience jet lag normally depends on how many time zones you cross and the distance travelled. The main symptoms are:
- Sleep disturbance - this is one of the most common problems and in severe cases people can find themselves wide awake at night while feeling very tired during the day.
- Confusion
- Headaches
- Lack of concentration, poor memory.
- Gastric upsets - diarrhoea, nausea, loss of appetite etc.
- Anxiety
- Disorientation, feeling light-headed
- Irregular periods can occur in women who travel frequently.
- Movements are clumsy, un-coordinated.
- General ill feeling, muscle pain and sweating.
However the circadian cycle can cause more than jet lag. Sleep disorders as well as obesity and diabetes have all been linked to problems with these body rhythms.


Have you ever suffered from sleep problems?
When the rhythm goes wrong?
To finish off we'll have a brief look at what happens when the circadian cycle goes wrong - and possibly leading to problems such as sleep disorders.
One of the most common sleep disorders is Circadian Rhythm Insomnia. This is where the person's natural rhythm of 'dark-sleep, light-awake' is disrupted for some reason. The most common causes for this disruption are:
- Jet lag - usually this will correct itself unless you are someone who constantly travels through different time zones.
- Shift work - people who rotate shifts can have sleep problems and also those who work constant/frequent night shifts.
- Advanced or delayed sleep phase syndrome - these conditions involve people becoming tired and then alert at inappropriate hours of the day and night.
- Non 24-hour sleep/wake disorder - this involves periods of insomnia that tend to occur at different times each night. People may wake up late in the morning for example and fall asleep later at night. They will also experience periods of falling asleep perhaps in the evening and waking up in the early hours of the morning.
The treatment for circadian sleep disorders depends on the particular sleep problem affecting the person. Once this is established a number of therapies can be used to try and get the person back into normal rhythms. For example some treatments might involve:
- Cognitive therapy
- Relaxation
- Self-hypnosis
- Bright light therapy
- Chronotherapy - this is where bedtime is slowly adjusted until the desired time for sleeping and waking is reached.
For many people a combination of techniques is often required rather than just one.
Lastly, if you do have problems with your sleep patterns, then speak to your doctor. Disturbed sleep doesn't just result in loss of a few hours rest that you can make up at some other time. Without regular, refreshing sleep, people can develop numerous physical and mental health conditions.
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Comments
Yes those were the good old days when sleep and its cycles weren't a problem. I just understand this waking up every two hours. Sure, there are some meds that tamper down those sleep interruptions but who wants to be on them forever? Besides you've got the tolerance factor. Anyway Helen, .learned some new things here. You heard that REM song called Daysleeper where he sings about Circadian Rhythms. And thanks for the thanks my friend, we'll see with the interview, and absolutely! Queen of the paranormal was a compliment by the person and I agree with them 100%!
So very interesting indeed seeker7 ; have a wonderful day and here's to many many more.
Eddy.
Hi Helen great well written article with great interesting information, and much of it i did not know before. Thanks for helping me learn more about this subject with this great informative article. Well done !
Vote up and more !!! Sharing !
Thanks! - great simple, accessible info. I am also interested in the tie-in between circadian sleep rhythms and the liver.
Thanks for sharing this very informative and interesting hub. Never knew about these cycles. Now I will follow my sleep patterns more closely. Passing this on.
This is a really interesting hub Helen, got me thinking about all sorts of things, like are the SCN messages affected by the loss of sight,
So many factors change our sleep pattern. I am one of those who is awake as soon as the sun shines through the blinds no matter how late I go to bed, so I find winters I wake much later.
I once did night shifts for six months and had to give it up, I was sleeping 12 hours a day and it still wasn't enough, and 'life' just didn't exist.
Hate jet lag because 2 or 3 days of the vacation are waste in recovering.
Anyways a super interesting and informative article Voting Up and sharing
Very interesting Seeker. I have always perferred the night. I like to go to bed around 1:00 - 2:00 and get up around 8:00 - 9:00. It just feels right and it came in mighty handy when I worked as a bartender.
I'm sharing this one! Thanks.
Hi Helen.
A very interesting and informative article you have written and researched.
The part about sleep disorder interested me as I am on the boarder line with Apnea. Which is abnormal pauses in breathing and this can last from at least ten seconds to minutes.
A good hub and good reading.
LOL Ghaelach
Great Hub Seeker7. I have found as I've got older that my sleep patterns have changed drastically. I used to have no problem sleeping, as a teenager I would joke that I could sleep pegged to a clothes line. Now I tend to have no trouble getting to sleep but wake after an hour or two then can't get back to sleep for ages. I have tried all sorts of medication and also retraining myself, but I think I'm at that age as you say where I need less sleep anyway. I do find that if I have a 'good' night and sleep right through I actually feel worse than if I'd been awake half the night! I don't seem to suffer though. Voted up, useful and interesting.
seeker7, thanks for this outlook and i never knew exactly what circadian cycles were until i came across your hub. thanks again. voted up.
Very interesting hub. Most of the people I work with have to do night shifts part of the time, some find it very disruptive and feel " jet lagged." Don't think I could do it! Disruption of the Circadian cycle can be stressful.
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