Biorhythms at the beginning of this century medical scientists made a surprising discovery : that we are built not just of flesh and blood but also of time . they were able to demonstrate that we all have an internal " body clock " which regulates the rise and fall of our body energies, making us different from one day to the next .the idea of an internal " body clock " should not be surprising , since the lives of most living things are dominated by the 24- hour night - and - day cycle . the most obvious feature of this cycle is the way we feel tried and fall asleep at night and become awake during the day . if the 24- hour rhythm is interrupted , most people experience unpleasant side effects . as well as the daily rhythm of sleeping and waking we also have other rhythms which last longer that one day and which influence wide areas of our lives . most of us would agree that we feel good on some days and not so good on others . scientists have identified the following three biorhythmic cycles : physical , emotional and intellectual . each cycle lasts approximately 28 days and each is divided into a high energy period and a low energy period of equal length . during the low energy period we are less resistant to illness and tire more easily . the low period puts energy into our " batteries " for the next high period . during the high energy period of a physical biorhythm we are more resistant to illness , better coordinated and more energetic . the " critical " or weakest time is the time of changeover from the high energy period to the low energy period , or vise versa. this " critical " time usually lasts a day . on the critical day of a physical biorhythm , there is a greater chance of accident and illness . human experience is always individual and we each have our own biorhythmic experiences . some people experience such enormous physical turbulence on their " physically critical " days that they have to go to bed . перевод
