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.
Dr Samantha Brooks is a UK neuroscientist working with
University of Cape Town, specialising in the neural correlates of impulse
control from eating disorders to addiction.
For more information on neuroscience at UCT and to contact Samantha, see
www.drsamanthabrooks.com.
