Cat Naps, Seasons and Body Clocks

‘The woods are lovely, dark and deep, but I have promises to keep, and miles to go before I sleep.’

The words of the poet Robert Frost will ring true for many readers who stretch the working day into the dark hours whilst others sleep. However, not even the most hardened workaholic or insomniac can run in the fast lane without the occasional pit stop. Our bodies are influenced by a circadian rhythm, whereby we experience a dip in our state of alertness twice in every twenty-four hours. This produces a state of sleepiness at some stage during the afternoon, bringing the urge to ‘cat nap’. The good news is that research has shown that the performance of those who sleep for less than six hours at night and then power-nap during the day is as good as those who sleep for longer at night. Indeed, a post-lunch nap improves work performance into the afternoon and early evening.

The circadian rhythm is influenced by how hungry we are. Our bodies have a mechanism whereby the brain keeps us alert when we need food; a mechanism which switches off when we have satisfied our hunger. That is a second reason why the urge to nap in the afternoon is irresistible for many, and explains why we have trouble sleeping when we are hungry.

However, our body-clocks have a greater influence than just affecting our state of alertness. The author Ernest Hemingway was showing more insight than he realised when he half-jokingly said ‘I love sleep; my life has a tendency to fall apart when I’m awake’. It is estimated that the body-clock controls some 15% of the activity of our genes; which means that disruption of the body-clock can affect a long list of bodily functions apart from sleep patterns. Our metabolism is very sensitive to such alterations, with the effect that insomnia, mood changes, heart disease, cancer and disorders of the brain can result. Because the body cannot fight infection until it recognises that one exists, we are more prone to infection at times of day when our metabolism and wakefulness is at its lowest ebb. Interestingly, research has shown that patients with septicaemia (blood poisoning) are at greater risk of dying between 2 a.m. and 6 a.m. This has in turn started scientists looking at what the optimum time is for antibiotic administration in order to fight infection with greater success.

When to give medication is also a question in respect to heart disease and high blood pressure. Both of these conditions are linked to high levels of a chemical called aldosterone. The latter is affected by the circadian rhythm, which means that drugs controlling blood pressure may be best targeted at specific times. Death in the early hours is an occurrence well known to doctors and funeral directors; and for those living near natural waterways, it is noticeable that the time of demise often occurs when the tide is out. Given the various research we are commenting on, this is perhaps not such a daft observation as previously thought.

Finally, the seasons also play a part in our well-being. Once again, research has found that blood pressure is better controlled during the summer, with the rates of heart attacks and strokes being higher in winter. This may not be just because of the cold weather, as people tend to exercise less, eat more, and increase weight during the winter. Diets during the winter months also tend to be higher in salt content.

All in all, it is increasingly clear that there are forces at play which influence us in more ways than previously imagined. Our individual lifestyle is a key factor, and armed with the knowledge of such research as above, it is open to us to take measures which may have a profound effect on our well-being. As Leonardo da Vinci said, ‘a well spent day brings happy sleep’. It may also bring health and a long life.

(First published in the Scunthorpe Telegraph, Thursday, 1st March 2012)