Spring is in the air as we emerge from the dark, wet winter months in Cape Town.  But how do our brains enable us to sense the changing of the seasons, and how are our biological rhythms formed?

 By Dr Samantha J. Brooks Ph.D.

One may think that it is only women who have a biological clock, but in fact we all have brains that govern – and are governed by – daily, monthly and yearly cycles. Neuroscientists know this because when participants are placed in isolated circumstances during research studies, the usual sleep-wake cycles, monthly fluctuations (applicable to both men, in the form of testosterone production, and women, in terms of oestrogen cycles) and yearly hibernation patterns remain, despite the changing external circumstances. For example, we all know how groggy and jet-lagged we feel after a long-haul flight, particularly when we travel West to East as our brain tries to adjust to the change in light to dark cycles. And if you’ve ever moved from the Northern to the Southern Hemisphere, it takes a while for the brain to catch on to the fact that winter is now in July, and the height of summer is in January! How then, do our brains cling to an internal body clock, even when the external surroundings change?

CLOCK genes help to regulate the systems within the brain that determine our sleep/wake and annual cycles, and can be found in most organisms and animals on earth. They are self-sustaining regulators or biological pacemakers for physiological and psychological processes such as core body temperature, blood sugar, blood pressure, food intake, cognitive performance and mood. In terms of brain areas, the supra-chiasmatic nucleus in the hypothalamus receives information from the eyes about darkness and light. This may partly explain why shift-workers such as nurses, doctors, late-night shop keepers and long-distance lorry drivers are most prone to disturbances in their biological rhythms, moods, and even food intake (people with irregular working patterns are more likely to gain weight). Other brain areas include the pineal gland, which secretes the hormone melatonin in to the blood stream to paralyse muscles, particularly during the dark night hours.  CLOCK genes also influence the growth of brain cells, and as such may be related to how well we create new neural pathways through learning. If we are flexible and can learn to adapt quickly, then jet-lag and out-of-hours shift work may not become a problem for too long.  The issue with jet-lag and out-of-hours work is that in the longer term, it can lead to cognitive deficits and neurological dysfunction, to the point where memory and hand-eye coordination deficits become dangerous to the person and to those around. The changing of the seasons, while a bit discombobulating, happens at a slower pace than jet-lag for example, and coincides less with cognitive deficits.

Nevertheless, we must try to remain flexible during the changing seasons, so that our circadian rhythms do not become irregular for too long and so that we can better adjust to new external circumstances (e.g. moving from dark winter months to bright, summer days).  Irregular circadian rhythms can lead to various psychiatric disorders, including major depression, bipolar disorder, schizophrenia, anxiety, stress dysregulation, eating disorders, drug addiction, and alcoholism, as well as age-related cognitive deficits including Alzheimer’s disease. The transition from winter to summer is always easier than from summer to winter, but still for some it can be a distressing time, as the body has to readjust to an altered external routine. The good news is that there are mainstream methods available to strengthen our ability to be cognitively flexible, so that our brain can quickly adapt to a new external situation, whether it be a new time zone, hemisphere, country, job or season. One method that has become popular in recent years is mindfulness therapy, which teaches a person to reconnect with the sensations arising from the body (physiological and emotional) and to not focus, or ‘latch-on’ to changing external factors. One popular mindfulness technique is called ‘the body scan’, which can easily be done at home and encourages people to focus on the feeling of different body parts, from toes to the top of the head. Such a practice can really help to direct attention away from the altered external reality, and towards the body’s natural rhythms. 

So as we approach summer once more in Cape Town, try to follow some mindfulness links on the internet, which will help to stave off any readjustment issues one might have to the changing seasons. And by doing so, our minds and bodies will be in tip-top shape to enjoy another glorious summer in our beautiful city.

Click to read all previous articles by Dr Samantha J. Brooks Ph.D.

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