Many years ago, in one of the last projects my research group conducted, we found that people with the erratic bowels of IBS also had erratic eating patterns, erratic moods and erratic sleep. Perhaps, we thought, disruption of some central regulator was causing a widespread disturbance in bodily functions. Unfortunately, we didn’t submit our results for publication, always expecting that we might go back to them later. We never did. So 25 years on, is there any evidence that such a regulator exists and if so, what factors affect it?
All bodily systems are fundamentally rhythmic, until something happens to disrupt them. Heart rate may be accelerated and destabilised by exercise or stress, respiration affected by fear and surprise, regular intestinal contractions disrupted by eating, brain waves altered by wakefulness, the menstrual cycle arrested by pregnancy. It’s like each organ possesses a clock or oscillator that keeps it ticking over until some demand is made on the system. In the gut, eating entrains the function of the stomach, gallbladder and small intestine, which will in turn suppress appetite. It’s a feedback loop, which can nevertheless be affected by sleep and perturbed by stress.
The most remarkable body clock is the one that regulates our sleep wake cycles. This is controlled by the same genes that are responsible for DNA repair, and in the simplest organisms may act to synthesise the proteins that protect DNA from ultraviolet (UV) light. The fifty thousand cells in the suprachiasmatic nucleus (SCN) are all synchronised to a cycle of 23.8 to 24.8 hours, even in people who are totally blind. UV light is the zeitgeber that sets the clock, but it takes several days before travellers adapt their sleep wake cycle to the new time zone and even longer for eating and defaecation to lock on.
Circadian rhythms offer us insight into how genes control our behaviour and even our society. Before the advent of artificial light and 24 hour work, human beings were regulated by the sun. When it got dark, we all slept together like chimpanzees and when it got light, we woke up and hunted and foraged together. In contrast to traditional farming or hunter gatherer societies, suburban man’s sleep is shorter and more disrupted. He is also less well.
Sleep in humans is an active process, it’s a time where growth and repair takes place and when memory is consolidated. Nevertheless body movement and sensation are inhibited for much of the time during sleep, though gut movements and digestion still occur. Sleep exists in several phases, each associated with different brain wave (EEG) activity. These include light sleep, deep sleep and rem (rapid eye movement) sleep and occur in that order. Deep sleep is the most restorative phase, associated with growth, repair, restoration of immune function, memory consolidation and the pruning of synapses, whereby the brain reorganises itself. Rem sleep is associated with sleep paralysis and dreams, which replay significant events of the previous day in symbolic form creating themes for categorisation into memories. After a good night’s sleep you remember things better.
The whole sleep cycle lasts about 90 minutes, which is a similar length to the periodicity of the band of regular intestinal contractions, known as the migrating motor complex (MMC). The MMC occurs at night and is thought to clear the small intestine of bacteria or the remnants of the previous meal. Absence of the MMC is associated with disrupted sleep patterns and may contribute to bacterial overgrowth of the small intestine.
Sleep deprivation changes both mood and physiology. It is associated with irritability, overeating, infections, lack of concentration, difficulty remembering things and of course, sensitive and erratic bowels. IBS is often complicated by sleep disturbance. The association goes both ways; a traumatic event can both sensitise the gut and disrupt sleep; disrupted sleep impairs memory and learning and causes frustration and irritability, which triggers symptoms in a sensitive gut. Shift work is not a good option if you have IBS. Sleep disturbance can exacerbate every mental disorder and many physical diseases, including inflammatory conditions, obesity and even cancer.
Shakespeare recognized how sleep ‘knits up the ‘ravelled sleeve of care’ 400 years ago. Since then doctors and clinical scientists have endeavoured to optimize sleep in order to assist healing. Unfortunately many sedatives, antidepressants and tranquillisers disrupt sleep cycles, but recently clinical scientists have found that bright lights or hormones such as melatonin can reset a more natural sleep/wake cycle. There are, however, simple changes we can all make to try to ensure a good night’s sleep. These include eating earlier in the evening, reducing alcohol or caffeine consumption, not working on computers or watching television late at night, resting in the evening and going to bed at the same time every night and not too late.
Routines are important. They regulate our physiology, balance our activity, ensuring there is adequate time for work, for physical exercise, eating, socialisation, rest and sleep. They render life predictable, so we have more time to contemplate and reflect on what we are doing and why we are doing it. Routines are the basis of mindfulness.
It may be a function of our success as a species, that human beings are infinitely curious and inventive, always creating new ways of being and trying out new experiences. A regulated life of routines might seem the very antithesis of human evolution or personal development, but it in fact provides an essential platform for creativity. Most successful people adopt routines that give them a predictable time and space for creative work.
Unfortunately, life for too many of us, is unpredictable, too full of interruptions, responsibilities, obligations and deadlines. So many people try to pack in more than they can really cope with and keep their mood and physiology regulated. This might explain why over half of the population suffer from sleep disturbance, obesity, irritable bowel, food intolerance and other disorders of regulation. It is so often the changes in life that upset the irritable bowel and yet change can be a constant and ubiquitous aspect of the existence of so many people. An erratic bowel, eating pattern or mood may represent a life out of control and can all too often feed back and make it worse.
So as a first step towards bringing your irritable bowel under control, try to find the time to adopt healthy routines and stick to them. A balanced life is as important for our health as a balanced diet.