In our body there are many ‘body clocks’ that are operating often simultaneously throughout the day. These clocks are known as biorhythms or circadian rhythms and refer to the cycle of biological and physiological processes that fluctuate on a roughly 24–hour timetable. You may have noticed these tendencies yourself, feeling more energetic and alert during certain periods of the day and more lethargic and run down at other times of the day. Another example is that mental alertness tends to peak twice in a day, at 9 a.m. and 9 p.m., while physical strength tends to crest at 11 a.m. and 7 p.m.
While we all have circadian rhythms there are differences in the length of the cycles, which helps to explain why some of us are ‘night owls’ and others are ‘morning people’. There also appears to be a genetic component to our rhythms, which explains why some lifestyle habits such as staying up late appear to run in some families and not in others.
Melatonin secretion, body temperature, vascular changes and bowel changes, change throughout the day as part of our biorhythms at work. To highlight this further let us focus on melatonin, our sleep hormone, which is released at around 9 p.m. until 7:30 a.m. This sets in place our natural sleep cycle. For those of us who work late hours or night shift we are in direct contention with this natural cycle and this may lead to issues with sleep or other aspects of our health.
One of the worst work situations I have found myself in was when I was undertaking alternating night and day shifts at a hospital. No sooner would my body clock get used to a night-time routine than I would have to switch to a day shift and vice versa. I would constantly feel tired, have no appetite yet was gaining weight, and had great difficulty sleeping when I was meant to. After a while I found that my mood started deteriorating and looking back on the situation I was probably bordering on depression. The best thing I felt I could do in that situation was to not alternate day and night shifts but rather request from my manager at the time extended periods of day shifts followed by nights shifts and so on. This way I was granted at least 3–4 weeks at a time to get used to a new routine. This way my biorhythms had time to adjust.