1. The body’s natural timetable
Modern life rides roughshod over our internal clock. We want to believe we can do whatever we want at any hour of the day or night if we need to, be it having dinner at 11pm, or flying to New York at 4am, with no ill- effects.
However, millions of years of evolution have given our bodies a finely-tuned internal clock. Listening to these natural rhythms could be the key to a healthier and happier life.
3. CLICKABLE: Your body’s daily rhythms
Click on the hand icon to explore how hormones levels and blood pressure change during an average day.
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Not everyone's body clock runs to exactly the same schedule. The graph shows average levels.
4. The clock in your brain
So where in your body is this 'clock'?
Individual cells, cultivated in a petri dish, exhibit a 24-hour cycle in gene expression.
Cells like these make up a part of the brain (known as the suprachiasmic nucleus) that responds to external time cues (like changes in daylight). These cells trigger whole-body changes such as the hormone cycles depicted above.
Watch the video to see how the suprachiasmic nucleus activity changes throughout a day.
5. Ignore your body clock at your peril
Many studies have shown how shift working can be harmful to health, with effects such as depression and obesity.
Shift workers are at a higher risk of type 2 diabetes, heart disease and cancer. It isn't known precisely why this is, but food digestion is much impaired at night, so eating meals in the small hours may elevate blood sugar levels unhealthily.
Missing night-time sleep damages the brain itself, according to a French study of over 3,000 workers. This showed that reduced sleep impaired memory and slowed speed of thought.
Is a night shift always bad news?
Some people have no choice but to work night shifts, and for some they have benefits. For example, they could allow you to do the school run – or pursue the job of your dreams. But for health reasons , the consensus is that it's best to avoid shift work if possible.