You may think you're getting older and you'd be right. But you might be surprised to learn that not all of you is getting older at the same rate. Owing to a curious interaction between gravity and time, your head is probably a little bit older than your feet. A stronger gravitational field causes time to run slower. So unless you spend all your time in bed your head, which is further from the earth's gravitational core, is ageing faster than your toes. Perhaps that's why Fred Astaire was so nimble on his feet well into his 80s ...

There are no clocks adorning the walls of Las Vegas casinos. There are no windows, either. Presumably the management believes gamblers might get discouraged if they realised how quickly they were getting through their life savings.

Clock and watch advertisements generally show timepieces reading ten to two. The reason for this, apparently, is that the hands, when arranged in this way, form a sort of smiley face. Alternatively, if the maker's name is printed in the top half of the clock face, this time allows the hands to frame the brand name attractively. The clock that once appeared on the masthead of The Times newspaper showed a variety of times, but most often it was half past four - teatime.

Iceland is the only 'European' country that does not operate daylight saving time.

Most people spend between twenty-five and thirty years asleep. The average British male spends approximately 13 months of his life shaving. The average American spends six months of his or her life waiting at red traffic lights.

A second is defined, rather mind-bogglingly, as 'the duration of  9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom'. A millisecond is one thousandth of a second. A microsecond is one millionth of a second. A nanosecond is one billionth of a second. A picosecond is one millionth of a microsecond. A femtosecond is one millionth of a nanosecond. An attosecond is one quintillionth of a second. Just to put this in context, an attosecond has the same relationship to a second as a second has to 31,709,791,983 years.

By tradition, clock faces that show the hours in Roman numerals use the apparently incorrect IIII to indicate 4 o'clock, instead of the more usual IV. (One high-profile exception to this tradition is Big Ben, which uses IV.) No-one knows precisely why this is, but one legend holds that the King 'corrected' his clockmaker for using IV and the clockmaker didn't dare to argue. More mundanely, it seems that IIII and IV have been interchangeable as ways of indicating the number 4 for centuries.