Category: Longevity & Health

Your chronotype describes your natural preferences for when you like to rise in the morning, and the time by which you’d prefer to go to bed at night. You will be aware of your most energetic and productive time of day, and conversely, when you start to lag. Put simply, we’re describing a spectrum running from morning types (larks) to evening types (night owls), with some of the population lying in between.

Due to work and other commitments, our schedules often cannot accord with our natural inclinations. It’s worth thinking about our chronotype because then we can be aware of any associations it may have with a greater tendency towards certain behaviours, imbalances or even disease.

The Different Chronotypes

Chronotype can shift during life: children are often larks, become night owls in their teens, then can shift back in adulthood. Older people may often be larks once again. It can also be influenced by genetics, cultural norms and light exposure.

Around 15% of the population are early risers, and particularly productive from dawn until noon. Another 30% are night owls, and productive at night; creative and artistic types can fall into this category. Most people, that is 40%, are most productive between 11am and 6pm, and their activity aligns with the sun. The final 15% of the population has difficulty establishing a sleep routine. Their productivity window may be from 10am to 2pm.

Insufficient sleep can affect anyone’s health, but if you are a night owl who needs to be up early for work, college or to get the kids ready, then follow all the usual sleep hygiene measures and try to establish a regular bedtime.

Chronotypes and Health

Although chronotype is just one of many health determinants, it’s useful to be aware of some of the associations that research has uncovered. That way, you can try to make sure that other, controllable factors aren’t going to conspire to further increase your risk of developing certain problems. Being a night owl may slightly increase the risk of anxiety, depression, eating disorders, obesity, type 2 diabetes and sleep apnoea for example.

Elderly individuals with an evening chronotype are more likely to be current smokers, have more sleep disturbance, engage in more sleep-interfering behaviours (evening caffeine or alcohol consumption, heavy meals before bedtime), and to have lower physical activity.

A Finnish study found evening types had a 2.5 fold increased risk of developing type 2 diabetes compared with morning types. Evening chronotype may be more associated with diabetes in men and metabolic syndrome in women.

Chronotypes and Eating Habits

Curious dietary patterns have emerged in various studies. Remember these are associations, some of which are not altogether surprising, but causality has not been established. In adolescents, evening types consume more coffee, energy drinks, alcohol and fast food. Young adult evening types can have inadequate intakes of several minerals and vitamins.

Morning chronotypes exhibit greater regularity in their eating behaviour. Adolescent evening types exhibit greater differences between weekday and weekend breakfast times. This is concerning given that patterns at this age can be laid down for life and that irregularity of meal patterns has been identified as a risk factor for cardiometabolic disorders.

Turning to adults, in a UK survey morning types consume 25% more servings of fruit and 13% more servings of vegetables per day compared with evening types. In a Finnish survey, those with a leaning towards the morning chronotype consumed more wholegrains, rye, potatoes and vegetables, while those leaning towards the evening type consumed more alcohol, sugar and chocolate. Evening types were more likely to be smokers, physically inactive, and have lower perceived health quality.

Adults with an evening chronotype skip breakfast more often than do individuals with a morning chronotype, and breakfast skipping has been related to lower physical activity in some studies.

Summary

A good deal of further research will be needed to establish causality in the above health observations. On the face of it, data suggests being a night owl is not particularly good for us. For now, if it just makes you consider how a later bedtime might in subtle ways lead to less healthy habits and eventually poorer health, then this will have been a useful read.

From the traditional Chinese medicine perspective, you may recognise that aligning our rhythms broadly with sunrise and sunset, and cultivating regularity of mealtimes, are principles that have been taught for centuries.

Further reading: (1) Chronotype: Implications for Epidemiologic Studies on Chrono-Nutrition and Cardiometabolic Health. Advances in Nutrition, January 2019. (2) Editorial: Chrononutrition and health. Frontiers in Nutrition, 14 November 2024.

Introduction

Here, I offer you a brief insight into ancient Chinese wisdom, and show with the aid of some examples, how well it resonates with the results of modern medical research. If you take away a flavour of this short article and change just one thing in your life as a result, then your time reading it will have been well spent.

The Chinese have long been interested in lengthening life and maintaining youth, and this has informed medical practice since ancient times. “Chang shou” or long life, is considered a blessing of heaven: it is a reward to be reaped for following the teachings of traditional Chinese medicine, about work, rest, diet, dress etc. (For some specific examples of these teachings, please read some of my Seasonal Tips.)

The idea of such preventative medicine appears in the classic texts of two millennia ago: “To wait for the battle before forging the weapons, to wait until one is thirsty before digging the well, is this not too late?” It is often said that people in those days, would therefore attend for acupuncture and advice at regular intervals during the year, most usually at the change of seasons, because that is when we are more vulnerable to imbalance.

Now we shall look at just two categories from a long list which the Chinese refer to as the causes of disease: these will be our emotional life, and our diet/eating habits. Bear in mind that moderation in all things, serves us well: to overemphasise exercise, at the expense of say diet, is not helpful.

Our Emotions & Their Health Implications

“When faced with something exasperating, one should calmly consider which is more important, anger or health.” (Cao Tong, Qing dynasty AD 1644-1912).

Emotions are considered in Chinese medicine, to harm us when we experience them too intensely or for too long: to be annoyed about a speeding ticket the day you have opened the envelope, would be understandable; to be completely enraged, or to still be angry six months later, would not! Indeed modern research shows a bout of intense anger increases the risk of a stroke within 2 hours, by a factor of 14 (Neurology Journal 2004), and increases by a factor of 17, the likelihood of a potentially fatal heart rhythm disturbance (Circulation Journal 2004). By comparison:

“Laughing makes you ten years younger.” (Chinese saying)

If things frequently wind you up, try to practise creating a space between the trigger, and your reaction. You then have a better chance of seeing that you’ve a choice between your old habitual reaction, and a new response which is less harmful to you.

For good health and a sense of well being, we need to promote a harmonious flow of Qi in the body. This is achieved by meditation, relaxation, exercise, happiness, and by cultivating a free flow of all our emotions, such that particular ones do not significantly linger or predominate.

“Flow with whatever is happening and let your mind be free. Stay centred by accepting whatever you are doing.” (Chuang Tzu c. BC369-286)

A lack of the more positive feelings, is seen as equally unhelpful: “People have illness because they do not have love in their life and are not cherished.” (Sun Simiao AD581-682) From the modern medical profession,”Those who feel lonely, depressed or isolated, are 3 to 5 times more likely to suffer premature death or disease. I don’t know of anything else across medicine that has such a broad and powerful impact.” (Dr Dean Ornish, Clinical Professor of Medicine at the University of California.) In the UK nowadays, depression is one of the top five conditions people seek acupuncture treatment for.

Diet & Recommendations on How to Eat

“Taking medicine but neglecting diet, wastes the skill of the physician.”  (Chinese proverb)

Diet is a cornerstone of good health. Chinese medicine can guide not only what we eat, but how we eat it. The ancient Yellow Emperor’s Classic of Internal Medicine, advised “The five cereals are staple food; the five fruits are auxiliary; the five meats are beneficial; the five vegetables should be taken in abundance.” 2500 years later, these priorities resonate strikingly with the UK’s “5-(portions of fruit & veg) a-Day” campaign. Over the centuries, subsequent texts reveal sophisticated developments in the use of food, including the transition to cooked food, made possible by drilling wood to create fire. Yi Yin in the Shang dynasty (BC1600-1046) emphasised that physicians should use the right kinds of food to help cure disease; food had now become equal to medicine.

In essence, we should supplement the mild, bland foods such as rice, vegetables and potatoes, with smaller amounts of nourishing, richer foods, such as fish, meat and dairy. To this can be added modest quantities of stronger flavours from spices or sugar. The balance between all these constituents is not rigid, but depends on our daily activity eg manual labour or lots of sport, versus a desk job. It also needs to accommodate our stage in life eg the growing teenage years, or pregnancy. It should even pay heed to the climate in which we live or work.

Foods today are chosen to support the patient’s Qi, balance yin and yang, and to treat illness. So when recommending particular foods to a patient, an acupuncturist will take account of a host of factors, including the person’s complaint, age, constitution, living and working environment etc. You do not have to be unwell to benefit from advice on the most appropriate diet for you; we should all choose foods which help maintain our health.

Finally, there is how we eat. Never skip breakfast. “People who eat breakfast are significantly less likely to be obese and suffer from diabetes than those who usually do not.” (American Heart Association’s 43rd Annual Conference on Cardiovascular Disease & Prevention). The emerging field of chrononutrition is exploring how the timing of what we eat, affects our health and wellbeing. Research suggests that consuming more of our calories earlier in the day aligns better with our circadian rhythms and supports metabolic health.

Try to take in most of your food up to and including lunchtime. Eat sitting, and relaxed, and not when stressed or angry.

Think about the food you are tasting, rather than devouring an entire plateful absentmindedly. Eat slowly and chew your food well.

“The stomach has no teeth”  (Chinese saying)

Eat only to 7/10 full. After the meal, rub your abdomen with a circular motion, 25 times clockwise then 25 times anti-clockwise. Finally, after a short rest at the table, take a stroll. The Chinese say,”Walk a hundred paces after a meal, and one can live ninety-nine years.”

Below, you will find some modern medical research from which you might wish to take a few healthy living tips.

Research from the Institute of Psychiatry, Psychology & Neuroscience (IoPPN) at King’s College London, suggests that viewing original works of art in a gallery setting can reduce key saliva markers associated with stress and chronic disease.

Fifty volunteers aged 18-40 were recruited from staff and students at Kings College. Half the group spent twenty minutes viewing original artworks at The Courtauld Gallery in London. The other half viewed reproductions of the same paintings in a matched, non-gallery environment. Participants were monitored for heart rate variability and skin temperature using digital watches to track levels of interest and arousal. Saliva samples were collected before and after viewing.

Levels of cortisol, a key stress hormone, fell by an average of 22% in the gallery group, compared to 8% in the reproduction group. Those viewing original art also had more dynamic heart activity, indicating that art engages the body through both emotional arousal and stress regulation.

Pro-inflammatory cytokines (IL-6 and TNF-alpha), which are linked to stress and a number of chronic diseases, dropped by around 28% for those viewing original art, while no change was observed in the reproduction group. This suggests art has a potential calming effect on the body’s inflammatory responses.

Dr Tony Woods, the study’s senior author from King’s IoPPN said, “Our unique and original study provides compelling evidence that viewing art in a gallery is ‘good for you’ and helps to further our understanding of its fundamental benefits. In essence, art doesn’t just move us emotionally — it calms the body too. Stress hormones and inflammatory markers like cortisol, IL-6 and TNF-alpha are linked to a wide range of health problems, from heart disease and diabetes to anxiety and depression. The fact that viewing original art lowered these markers suggests that cultural experiences may play a real role in protecting both mind and body.”

(The Physiological Impact of Viewing Original Artworks vs. Reprints:
A Comparative Study. Institute of Psychiatry, Psychology and Neuroscience, Department of Psychological Medicine, King’s College London. Kings College News Centre, accessed 28 October 2025.)

A collaborative study between the University of Helsinki, Natural Resources Institute Finland and Tampere University, has demonstrated that just one month of indoor gardening enhances immune regulation, can increase the bacterial diversity of the skin and is associated with higher levels of anti-inflammatory molecules in the blood.

It has previously been shown that contact with natural microbially-rich soil media alters the human microbiota, that is the 2 kg or so of microorganisms within each of us. Beneficial microbial exposure has decreased among people living in urban areas and they have distinct microbiota compositions compared to their rural counterparts.

Evidence suggests that home surroundings play a key role in determining microbiota-related health outcomes:

• Surroundings of forest and agricultural land during the first year of life are inversely associated with the risk of atopic sensitization and type 1 diabetes.
• Biodiverse and green living areas correlate with better respiratory health.
• Diverse garden vegetation and outdoor nature-related activities have been linked to health-related changes in the gut microbiota composition.
• Living in rural or farm-like conditions is directly associated with a diverse microbiota and a well-functioning immune system.

Participants in this research were recruited from the cities of Lahti (population > 120 000) and Hyvinkää (population > 45 000) in Finland. They had to be broadly healthy, with for example certain immune-mediated diseases excluded. They were randomised to either an intervention or placebo group and were asked to fill out questionnaires assessing their living conditions and lifestyle, including medication, food supplements, diet, outdoor activities and hobbies, and any contact with soil. Hand washing habits were also recorded. Samples from thirteen placebo and fifteen intervention group participants were used in the analyses. The participants’ ages ranged from 29 to 72.

Participants were provided with a planter, seeds, plants, and growing medium. The placebo group used horticultural peat, chosen because of its low bacterial diversity. The intervention group used the same horticultural peat mixed with a microbiologically rich compost-based mixture, containing composted materials such as tree bark, mulch, dung, deciduous leaf litter, peat, agricultural sludge, and Sphagnum moss.

Both groups were provided with the same seven crop species: lettuce, white mustard, radish, garlic, ginger, pea and fava bean. They were instructed to sow their seeds and daily tasks included both soil and dietary exposure: monitoring moisture levels by inserting a bare finger deep into the growing medium, watering, harvesting, and resowing. Blood samples, and skin swab samples for bacterial analyses, were collected at the beginning of the trial and at one month. 

After one month, plasma anti-inflammatory cytokine IL-10 and skin bacterial diversity both increased in the intervention group. Since the diversity of bacteria increased in the intervention but not in the placebo group, the results suggest that handling a microbially-rich growing medium enriches the skin microbiota. Immune modulation was also enhanced in the intervention but not in the placebo group.

“The findings are significant, as urbanisation has led to a considerable increase in immune-mediated diseases, such as allergies, asthma and autoimmune diseases, generating high healthcare costs. We live too ‘cleanly’ in cities,” says Doctoral Researcher Mika Saarenpää. Microbial exposure can be increased easily and safely at home throughout the year. The space and financial investment required is minor. In the study, the gardening took place in regular flower boxes, while the plants cultivated, such as peas, beans, mustards and salads, came from the shop shelf. Changes were observed in only a month, but as the research subjects enjoyed the gardening, many of them announced that they would continue the activity and switch to outdoor gardening in the summer.

Noteworthy for gardeners is that this research suggests that peat, the most widely used growing medium in the world, does not appear to bring the health benefits associated with a medium mimicking diverse forest soil. 

(Urban indoor gardening enhances immune regulation and diversifies skin microbiota — A placebo-controlled double-blinded intervention study. Environment International, May 2024.)

If an iron supplement has been recommended to you by a professional, then here are some useful guidelines for taking it. If you are unaware of these considerations, you won’t get the best value for money from your supplement and it may take longer than necessary for your iron levels to get back up to normal.

A good deal of research has been conducted in this area, much of it on individual dietary components in order to minimise the variables. When a typical complete diet is considered, the results may be a little different, but it probably won’t invalidate the broad recommendations that follow from what I have written. This is a surprisingly complex subject and there is more waiting to be discovered, but treat this as a simplified summary.

Iron is unusual in that 90% of our daily needs are met from within, from the natural breakdown of old red blood cells in fact. Some iron is lost by for example menstrual bleeding and the shedding of skin cells. In adults, the sum of these losses must be compensated for by diet. Certain diets and medical conditions will mean that supplementation is beneficial at intervals.

Haem and Non-Haem Iron

Dietary iron comes in two forms:

Non-haem iron is found in plant foods but also occurs in animal tissue. It is significantly less well absorbed than haem iron [1], so vegetarians and vegans have to be more vigilant when it comes to ensuring sufficient iron in their diets. Nevertheless, these foods are important components of a well-balanced diet.

Inhibitors of Iron Uptake

Some components in our diets can inhibit iron uptake. These are phytates, polyphenols, calcium and animal protein from milk and eggs. Taking these in order, phytates are present in plant-based diets in foods such as whole wheat, oats, rice, black beans, pinto beans, kidney beans, soybeans, peanuts, lentils, walnuts, pine nuts, almonds, sesame seeds, potatoes, beetroot, turnips and carrots. Once again, these foods are important elements of a well-balanced diet.

Phytates form complexes with iron, zinc and calcium rendering those minerals hard for the body to absorb. In practice, this would suggest it’s best not to take your iron supplement with your oat porridge in the morning, because you have the presence of phytates and milk.

Next on the list of inhibitors come polyphenols. These are found in some fruit, vegetables, red wine and teas including herbal teas. They offer many benefits including anti-inflammatory and anti-oxidant properties and positively should be part of your diet. They do however, inhibit iron absorption. This means don’t have black tea, coffee, cocoa, or herb teas like chamomile or peppermint (the common ones I found referenced in the research literature) at the same time as your iron supplement. Black tea appears the most inhibiting and red wine the least. The addition of milk to tea and coffee appears to make no significant difference.

Another common inhibitor is calcium. This seems to have a limited effect on haem and non-haem iron absorption, being taken up preferentially at the expense of the iron. In the diet as a whole, it is probably less of an issue, but it would seem sensible if you have also been recommended to take a calcium supplement for osteoporosis say, not to take it at the same time as your supplemental iron.

Finally, animal proteins such as milk and egg proteins, are also inhibitors of iron uptake, as is soy protein. It would follow that avoiding milk, eggs or sports protein supplements with your iron, would make sense.

Enhancers of Iron Uptake

Next we come to the two main enhancers of iron uptake: vitamin C and animal tissue. Vitamin C is able to reduce Fe3+ to Fe2+ (see [1] below). Let vitamin C be a trump card for you. It can counteract the unhelpful effects of all the inhibitors mentioned above and is a good supplement to take alongside your iron.

In vegetarian and vegan diets, fruit and vegetables rich in vitamin C can be used at every meal to enhance uptake of the non-haem iron in those meals. Kiwi fruit for example would be a good dessert. Connected with that though, be aware that cooking and storage can degrade vitamin C in food. This applies to freezing, and especially to the boiling of vegetables where vitamins C and B dissolve in the water which gets discarded.

Distinct from the animal-derived proteins mentioned above as inhibitors, animal tissue on the other hand is an enhancer of iron uptake. This includes meat, fish and poultry.

Summary

All you really need do is think about the content of your meals from the above perspectives, and you’ll probably be able to settle on a regular time of day for your supplement. For example, if your breakfast is a lovely healthy bowl of muesli (phytates) with berries (polyphenols) and milk (animal protein), then you should probably choose a time later in the day to take your iron.

Resist the temptation to get too tied in knots over these suggestions, or to avoid the inhibitors because in themselves, they are healthy foods offering a range of benefits. The most important thing is that you take your iron supplement at some point in the day, and if you can heed these tips, then so much the better. There is an abundance of research available and I have listed below some starting points if you are interested.

A relatively new school of thought is also that iron absorption may be better when supplements are taken on alternate rather than on consecutive days. The research [2,3] has often used quite high doses of iron and it may not be applicable to all patient groups. It may be helpful for patients who get unwanted digestive side-effects.

[1] If you are curious about the difference in our ability to absorb these two forms, here is an explanation for those interested in chemistry. Non-haem iron is in the ferric or Fe3+ form. The stomach is a highly acidic environment, but the duodenum far less so, meaning that ferric iron would precipitate out when it arrived there. To be successfully absorbed in the small intestine, ferric iron must be soluble and form bonds with helpful organic molecules in the diet, though it can also end up bonding with molecules which inhibit its absorption. Haem iron by contrast is in the ferrous or Fe2+ form and encounters none of these hurdles so is more readily carried into the intestinal absorptive cells.

[2] Iron absorption from supplements is greater with alternate day than with consecutive day dosing in iron-deficient anemic women. Haematologica Journal, May 2020.

[3] Alternate day versus consecutive day oral iron supplementation in iron-depleted women: a randomized double-blind placebo-controlled study. eClinicalMedicine, Lancet Publications, November 2023.

Iron bioavailability and dietary reference values. The American Journal of Clinical Nutrition, May 2010.

Soy protein, phytate, and iron-absorption in humans. American Journal of Clinical Nutrition, 1992.

Inhibition of non-haem iron absorption in man by polyphenolic-containing beverages. British Journal Nutrition, 1999.

Calcium supplementation—effect on iron-absorption. American Journal of Clinical Nutrition, 1991.