Bio-rhythms or circadian rhythms

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The body has its own internal clock, which tells us exactly what time of day it is. It is very common in chronic fatigue syndrome (CFS) and other illnesses to see this biological clock upset. Anybody who has experienced jet lag knows exactly the sort of sensations when one’s biological clock is out of kilter! In chronic fatigue syndrome the commonest disturbance seems to be that the biological clock is moved on from that in the health population, so CFS sufferers naturally fall to sleep late at night and naturally wake up late in the morning. For obvious reasons this is anti-social, but it is likely that this loss of a normal circadian rhythm gets in the way of recovery. One possible reason for this has to do with Human Growth Hormone. This is produced during the hours of sleep before midnight and is an essential part of normal metabolism. Even our immune cells are tuned in and are non-active at certain times of the day. If sufferers do not sleep before midnight, their levels of human growth hormone are less than optimal.

When the normal circadian rhythm is lost, there are things that can be put in place to help re-establish it.


Our biological clock is set by light. Electricity gets in the way here! Our forbears went to bed when it was dark, simply because it was cold, boring and probably expensive on energy to do otherwise. Their daily biological clock was reset daily. They slept longer in the winter as they went into a semi-hibernation state in order to conserve energy when food supply was low. Conversely, during the summer they had shorter sleeping hours and longer working hours in order to store up food and resources to allow them to survive the next winter. People living on the Equator, of course, have the same sleep requirement throughout the year, but the further away from the Equator one is, the more obvious is this change from winter to summer. We have lost respect for those annual rhythms – actually we all need more sleep during the winter than in the summer because we go into a state of semi-hibernation and our behaviour should reflect this. Many people get into a habit of sleeping shorter hours in the summer and sustain this same pattern through the winter artificially. As a result, as a nation we are chronically sleep deprived. The average sleep requirement is for nine hours, but the national average is 7 ½ hours. Lack of sleep is a major risk factor for heart disease, cancer and, of course, chronic fatigue syndrome.

The importance of darkness at night and light by day, together with its links to vitamin A, can be seen at Cambridge University Neuroscience Video. It must be VERY dark by night!


We can use light to help re-establish our biological clock. We need bright light during the day. This switches off melatonin production and melatonin is, of course, the sleep hormone. The best light is full spectrum light and we all prefer to sit in sunshine, or next to natural light from windows. Failing that one can use light from a full spectrum light box.


Conversely, at night we should use light, or rather darkness, to allow our own endogenous melatonin production to happen. The only way to do this is to be disciplined about the time at which one goes to bed, and not allow electricity to get in the way of adequate sleep. I often jokingly threaten my patients with cutting off their power supply to their house every night at 9pm, which would certainly help them to restore a more normal circadian rhythm! It may take some weeks or months for the body to adjust, but this is vital for short and long term health.

The bedroom should be dark for melatonin to be produced – light pollution is a major problem and blackout curtains may be necessary.

Light intolerance

Many of my ME/CFS patients complain of light intolerance and, indeed, the very sick ones simply do not tolerate light and have to lie in a darkened room. My guess is that this has to do with energy supply to the brain. The brain uses up energy in the form of ATP ten times faster than the rest of the body does. The most active part of the brain is the retina at the back of the eye – this needs a free supply of energy to function properly. In chronic fatigue syndrome energy supply is severely limited and my guess is that this explains the many visual symptoms that CFS patients complain of. It also explains why, as we age, we often get eye pathologies. This is for two reasons – firstly, we get less good at supplying energy because declining mitochondrial function is an inevitable part of the ageing process, and secondly, because the business of delivering energy generates large numbers of free radicals, which are potentially damaging to the eye. See Brain fog.


Broadly speaking, proteins and fats have a stimulating effect and fire us up whilst carbohydrates have a soporific effect and calm us down. Western diets are completely upside down – we tend to eat carbohydrates at breakfast and have our protein meals in the evening. We would function much better if we all ate a good fry up at breakfast in which proteins and fats predominate, mix of the two at lunchtime, but in the evening carbohydrates should predominate over proteins and fats. There should always be a good supply of fibrous foods since these are fermented in the lower gut by Bacteroides to supply short chain fatty acids. These are an excellent energy source and this is what prevents us from developing hypoglycaemia during the night. Indeed, my guess is that poor energy supply to the brain because of hypoglycaemia or because of low fat diets is the commonest cause of disturbed sleep.

I am not averse to people using caffeine during the day in order to fire themselves up. Whilst some people are intolerant or allergic to caffeine, for many it helps to enhance the difference between day and night. Be mindful that caffeine has a long half life for some people who are slow detoxifiers and should not be taken after 4pm, especially if sleep is an issue.

The correct evolutionary diet is the PK diet. Please see My book - Paleo-Ketogenic: The Why and The How and these links below:


If all the above interventions are in place, then the hormone messengers which control our bio-rhythms and many other aspects of life will also fall into place. However, as we age our ability to produce hormones declines; furthermore, in chronic fatigue syndrome it is very common to find poor levels of hormones. So there may be a good case for taking judicious amounts of hormones as we age, in order to maintain our biological clocks – some of these should be measured, some can be safely given without measuring.


This is a natural sleep hormone and its output declines with age. Melatonin is an excellent antioxidant and one could argue that everyone over the age of 60 should be taking 1mg – 3mg at night. Some people need slow release melatonin to carry them through the night. I often recommend up to 9 mg of melatonin to improve length of sleep and quality of sleep. See Sleep is vital for good health - especially in CFS

DHEA and cortisol

Ideally these two hormones should be measured by doing an Adrenal stress profile - salivary. However, I suspect that like with melatonin, levels of DHEA are affected by an acquired metabolic dyslexia – that is to say, as we age we get less good at making this. I used to treat DHEA deficiency with DHEA. However, I believe pregnenolone is more physiological because it is upstream of all adrenal hormones including progesterone and cortisol There is a good case for supplementing pregnenolone 20mg daily in all people over the age of 60, but if you wanted to be sure, measure the levels first. The same may well be true for cortisol, but really we should measure it to be sure. Cortisol is well absorbed through the skin and levels can be corrected or boosted with hydrocortisone cream or ointment. A normal adrenal gland should put out 20 – 25mg of hydrocortisone daily. A 1% cream or ointment contains 10mg of hydrocortisone per ml of cream, so 1 – 2ml rubbed onto the skin daily may be helpful

Thyroid hormones

These must be measured in all cases before considering replacement therapy. See Thyroid and Hypothyroidism. There is a synergistic relationship between thyroid and adrenal hormones and correction of thyroid hormones is also an essential part of correcting our circadian rhythm. See also this test - Thyroid profile: free T3, free T4 and TSH

Vitamin B12

A great many of my CFS patients get a clear physical and psychological boost from B12 by injection. Indeed, many comment that if they have their B12 injections at night it stops them sleeping! I can supply a Transdermal B12 spray from which I have seen good clinical results - see Transdermal micronutrients See also B12 - rationale for using vitamin B12 in CFS for details of B12 by injection.


Chocolate is made up of cocoa mass, sugar and milk. Cocoa mass is very good for us – it is derived from the cocoa beans and there is everything within a bean necessary to make a whole plant. Therefore, it is rich in micronutrients and antioxidants. Chocolate has a direct calming effect and for many people it is helpful taken at night. It does have a mild stimulant effect and some people do not tolerate it at night. The problem with chocolate is the sugar and dairy content – both these are addictive, more so than the chocolate itself. So the ideal chocolate wants to be high in cocoa solids and dairy free with minimal sugar content.


Alcohol is very damaging to circadian rhythms. Although initially it makes one feel sleepy and tired and can help one to get off to sleep, it will also produce rebound hypoglycaemia which disturbs sleep. See also Alcohol intolerance in CFS - gives us a clue as to the mechanisms of fatigue

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