How listening to your body clock can make you tick

If you really want to get ahead at work or in your studies, maybe you should listen to your internal body clock more. To the men in white coats, this phenomenon is known as circadian rhythm (circadian comes from the Latin for 'about a day'). To you and me, it's the way in which our bodies seem to be up for performing certain activities at certain times of the day.

Each of us has our own distinctive circadian rhythm or internal clock, which regulates our body, releasing chemicals and changing breathing and heart rates as we move through our 24-hour cycle. Studying these daily behavioural patterns has enabled them to discover the best time to for each of us to do all kinds of things, from studying for an exam to playing sport to having sex. The implications are huge. If you know when your body is most up for a particular task, you can plan around it, to make the best use of your daily energy. And that's not all. You are also about to hear the best excuse ever for your inability to get up in the mornings…

What type of bird are you? We're all on the same cycle, but some of us start — and finish — later than others. Sleepwise, we all fall somewhere along a circadian spectrum that has 'larks' at one end and 'owls' at the other. Owls wake early and are at their best in the hours leading up to lunch; larks struggle to get started after waking but come into their own as the day goes on, and are often quite capable of working into the small hours if need be. (By the way, all of us tend towards the lark end of the scale as we get older.)

Plan your day. Knowing where you fit on this spectrum is your first step to making the most of your internal clock. If you feel like sleeping at midnight you'll be mentally brightest from around 9-10am, and your afternoon 'down' — we all get one — will hit around 4pm. But the more of an owl you are, the later these times will occur, so plan your day accordingly.

Adjusting your pattern. Regular sleeping habits are essential to good performance. If you're a morning person but have got into the habit of going to bed later and later, it's vital to get back into a sleep pattern that suits you. Set a time for bed — ideally before midnight, say sleep experts — and stick to it, whatever you've been doing that day. (Don't worry if you can't sleep straight away: you will, with practice. In the meantime, do something relaxing like listening to gentle music.)

Re-setting the clock. Experiments in settings where there are no external cues to the time of day reveal that in most people the circadian cycle is actually about 25 hours long. Which is why it's good to take things a little easier on the weekends — it's a buffer period which allows you to get back in synch with your cycle.

Ease your way into the week gently. Don't start off too violently on a Monday morning. Because of the 25-hour cycle most of us are on, many of us are effectively suffering with a subtle form of jet lag on Monday mornings. (Which may explain why Monday between 8-9am is the most common time for heart attacks!)

Think, think! Generally, people are best at doing mentally demanding tasks in the morning, somewhere between 10am and noon — and certainly before lunchtime, which always produce a slump. Research from the Laboratory of Experimental Psychology, Sussex concluded that intellectual tasks are on average performed almost ten per cent better at 10.30am than in the evening.

Brain first, memory second. As a rule it's better to do purely intellectual and analytical work earlier in the day — and revision, retention-based work towards the end of your thinking session.

The rhythm method. Scientists say the body is most primed for sex (and fertilisation) in the early morning — when you first wake up. Levels of the hormones which stimulate the sex drive ' testosterone (in men and women), progesterone and oestrogen (in women) — are up to five times higher at this time of day.

Work that body! Exercise is best in the late afternoons and early evening, when muscles are at their warmest and most flexible. Not surprisingly, this happens to be the time when most Olympic records are broken. The happy exception here is sex, which turns out to be good at both ends of the day. Normally physical activity is stimulating — it increases blood pressure and heart rate, and switches the mind on — so shouldn't be carried out too close to bedtime. Sex, however, is unique in having a soporific effect.

And that classic excuse? 'Sorry I overslept. It's just that in circadian clock, genetic terms, I'm an extreme owl type.'

by Dan Fielder, editor in chief of Sticky Content, an editorial services company, is a health writer who has written for many leading magazines and newspapers.

What do you think? Are Circadian Rhythms new-age twaddle or does the time of day make a difference to your performance?