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Circadian Rhythms and Endocrine Disruptors

Updated on July 26, 2012

Ever wonder why some people just naturally seem to be early risers while others can barely crawl out of bed by mid-afternoon? The answer is in their biological clocks. Our biological clocks are what drive our circadian rhythms. We have sort of a “master clock”, located in the hypothalamus, which is made up of a group of nerve cells called the suprachiasmatic nucleus (SNC). The SNC contains about 20,000 cells. This master clock coordinates all the body clocks, keeping them in synch with each other.

One of the clocks controlled is that of our circadian rhythms, a group of mental, behavioral, and physical changes following a 24 hour cycle. These changes respond mostly to the light and darkness in our environment. Such rhythms are found in most living things, including plants and animals, and even microbes. Though they are produced by natural factors within the body, they are also affected by our environment with light being the main force behind the turning on and off of genes that control our internal clocks.

Our circadian rhythms regulate our sleep-wake schedules, body temperature, hormone release, and other bodily functions. They are very important to determining our sleep patterns. The SCN controls the production of melatonin in the pineal gland. Melatonin is the hormone which makes us sleepy. The SCN is right above the optic nerve, which relays information from the eyes to the brain. When incoming light is low, as at night, the SNC signals the brain to make melatonin, so that sleep may be brought on.

Numerous studies have linked our circadian rhythms to various sleep disorders, such as insomnia and disrupted sleep-wake cycles. Depression and bipolar disorder have been linked to abnormal circadian rhythms. There are several ways our circadian rhythms can be disrupted, jet lag and shift work being among them. There are also drugs and toxins which can have severe disrupting effects on our rhythms.

Much has been reported and recorded on the ill health effects associated with pesticides, insecticides, and additives in our food. More and more research shows these chemicals being released into our environment, as well as our food, serve to cause disruption in the functioning of the human endocrine system. They are referred to as Endocrine Disruptors, or EDC's.

The endocrine system is made up of 10 different glands, each having its own function in regulating and maintaining body functions. When the functions of the endocrine glands, and the levels of hormones are changed, many different illnesses can result. The effects of EDC's in connection with immunity, metabolism, and body organs can be disastrous.

Several studies have linked EDC's to alteration of the circadian “clocks” in the liver, as well as other organs. Since EDC's have a direct impact on altering and disrupting the levels of hormones, and the glands associated, circadian rhythms have been found to be impacted as well. At this time, there are questions whether the disruption of circadian rhythms are the key to tripping the trigger, so to speak, when considering the almost doubled incidence of diabetes and obesity since 2000.

Sleep disorders are another factor to contend with when dealing with diabetes and/or obesity. The question is: Which came first? The illness brought on by exposure to EDC's, or disruption of circadian rhythms due to exposure to EDC's?

If you have begun to experience unexplained trouble sleeping, or your sleep patterns seem to be erratic with no known cause, you may be suffering the effects of EDC exposure. To lessen your exposure to Endocrine Disruptors, you should make sure you read the labels before consuming processed food. It's better to stick to whole foods you cook yourself, but even with these you may be dealing with farming chemicals which have been absorbed into the plants. Stop using artificial sweeteners and flavors. Trade in your carbonated sodas for water. If you are a juice drinker, make sure you are only purchasing those without sweeteners added.

To bring your circadian rhythms back to normal there are several things you can do, once you've removed EDC's from your diet. Your bed is for sleeping, not watching television, doing last minute computer work, or eating. Try to stay consistent with bedtime hours. Go to bed at the same time every night, setting your alarm for the same time every day. This means even on weekends.

Don't pull the window shades down, or close the mini-blinds. Our bodies produce melatonin when our eyes don't register high levels of light. The more melatonin in your system when the alarm goes off, the groggier you will feel upon waking. When evening comes on, start dimming the lights to get that melatonin pumping.


Forget the midnight snacks. In fact, cut out all eating and drinks at least two hours prior to your scheduled bedtime. Circadian rhythms have been linked to meal schedules. Since we eat most of our meals during the day, that late night snack may trick your brain into responding as though it's the middle of the day. Melatonin production will be halted, which will result in you being alert when you need to be getting sleepy. In addition, waking up to visit the bathroom is a sleep disruptor!

Getting enough exercise has been linked to a good night's rest. However, if you exercise too close to bedtime, it can have the opposite effect. Exercising causes endorphins to be released which may make you feel very alert and energized. The idea is to use your muscles enough during your waking hours so that you will be ready for a rest at bedtime. It's best to make sure your workout is finished at least an hour before hitting the sack.

It takes some time to get your rhythms back to normal. If you experience wakeful periods during the night, it's recommended that you get up for a few brief moments rather than laying there staring into the dark. All you will do is become frustrated at not being able to sleep, which will make you feel more wide awake. However, do NOT turn the lights on and start watching television. After a moment or two of quiet thought, try to go back to sleep. No matter how sleepy you may feel when the alarm goes off, get up anyway. You'll be twice as tired when bedtime finally comes again!

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    • joecseko profile image

      Joe Cseko jr 

      16 months ago from New York, USA, Earth

      This is a good piece. I've been doing a lot of research on circadian and ultradian rhythms. I've recently written a piece of my own, though the focus of my article is narrower.

      Nice job.

    • profile image

      Meg Mahoney 

      5 years ago

      I am a researcher focusing on estrogen effects on circadian rhythms. I was interested to find your article here (and agree with everything you stated!). I was wondering what your references were with respect to EDCs on circadian rhythms. I have found some on dioxins and cadmium but there is relatively little research out there. I didn't want to miss something.

    • Terri Meredith profile imageAUTHOR

      Terri Meredith 

      7 years ago from Pennsylvania

      Well, it's never too late, is it? I've changed a lot of my own eating patterns and cut out as much as possible of the foods with known additives. The problem still rests with the fact it's becoming increasingly difficult to find any food that hasn't been subjected to alteration. It's an issue that isn't likely to go away without the voices of the consumers making it loud and clear that we won't accept poison. I like the pic of the doc too. Wonder if it's real?

    • profile image


      7 years ago

      I'm thinking that despite the fact that we've eaten a lot of "garbage" over the years, there are things we can do to improve our health and avoid some (if not all) of the junk that's out there. And who knows what positive adaptations our incredible bodies have made in order to circumvent or stave off these negative impacts? I don't know if you can see the ad below of the 72 year-old doctor with the six pack, but that gives me hope (unless it's Photo-shopped :-)).

    • Terri Meredith profile imageAUTHOR

      Terri Meredith 

      7 years ago from Pennsylvania

      Well, hello again!

      Thanks for your kind words. As for getting up a couple of times a night...I think that's something more related to female aging. (We have stuff that gravity pulls on! and of course having kids) :DD But, I can't help thinking so many of the minor things have turned into the majors with the advent of EDC's. I wonder if all the issues would be nothing more than small inconveniences if we hadn't already damaged ourselves unknowingly by eating the garbage we've done over the years?

    • profile image


      7 years ago

      Very informative. As someone who experienced problems sleeping for a good 10 years (from my mid 40s to mid 50s - I figured it was (peri)menopause), I now realize how important it is to be active during the day. I've had to force myself to take "exercise breaks" during the day since, as a writer, I am fairly sedentary. Following your sleep recommendations, as well as cutting back big time on caffeine consumption, has helped. I still get up a couple of times a night to go the bathroom, but I figure that comes with age. Great information on circadian rhythms and EDCs. Rated up and useful.

    • Terri Meredith profile imageAUTHOR

      Terri Meredith 

      7 years ago from Pennsylvania

      As someone who has always burned the candle at both ends, I didn't even realize how screwed up my sleep patterns were until I stopped working my last job. I was so exhausted that I became comatose seconds after hitting the sack. Now that I've got the time to actually sleep regular hours, I've run into problems. I've come to realize that all those years I was masking the problems through the demands of my professional position. I believe the majority of folks who suffer insomnia are probably truly suffering the effects of EDC's. The only thing we CAN do is to loudly voice our preferences for produce grown from "Heritage" seeds. And then work hard to have stricter regulations enforced regarding the open farming of biotech seeds.

    • Alastar Packer profile image

      Alastar Packer 

      7 years ago from North Carolina

      As one having trouble sleeping for some time(its more waking up every two or three hours) and following all the recommendations in this excellent article, that leaves only one possible culprit: Endocrine Disruptors- the chemicals in our food and environment which despite ones best efforts are impossible to avoid more or less. And what are we to do when even the organic food producers are pressured into buying seed from non-natural sources approved by the USDA or FDA which in some cases has the pesticides built into the food structure its self. Is there an answer? Do the majority of people even really care?


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