Leading Article: Importing the siesta: we should sleep on it

MANY of us return from holiday tempted by the idea that the siesta should be imported into Britain along with olives, tomatoes and other products of Mediterranean civilisation that already enrich our lives. It is among the more attractive foreign customs, and often insinuates itself almost unnoticed into the weekends of returning travellers.

Doctors, however, disagree on how far it should be encouraged. Some are actively hostile, arguing that siestas can give some people too much sleep and contribute to insomnia at night. Others are more positive. Professor Ian Hindmarch, head of the sleep laboratory at Surrey University, says that afternoon sleep provides proportionately more of the deeper sleep needed for recovery. Dr Andrew Smith, a psychologist at the University of Wales, has deployed science to confirm the obvious, which is that concentration drops in the afternoon as brain waves follow a nocturnal rhythm. A French expert has found that industrial and road accidents increase in the afternoon, although wine probably plays a role in that phenomenon.

Unfortunately for those who would like dormitories to be obligatory at places of work, science has not yet proved conclusively that the siesta prolongs life, improves health or raises efficiency. Research is finding a lot to say about how best to arrange shift work and cope with travel across time zones, but in so far as there is a broad consensus on sleep, it points to the conclusion that the only important requirement is to get enough of the right type. Quantity can vary for each individual, and timing is largely a matter of conditioning and social convenience.

Almost any structured sleep pattern is probably 'unnatural'. Animals and babies sleep when they have eaten enough. People cut off from natural light tend to opt for a 25-hour cycle. Fitting sleep into modern society is only part of a wider process of adaptation. It is threatened more by noise and stress than by whatever timetable happens to be the norm in a given society.

Siestas are a natural adjustment to hot climates, where it is foolish to work through the hottest part of the day, and they flourish most easily where home is near work. In places such as Spain and northern Italy, however, they are losing ground in the big cities because of air conditioning, greater distances between home and office and the need for constant contact with other parts of the world.

There is, however, something useful to be learnt from scientific interest in the siesta: individual needs vary, post-prandial drowsiness is natural, and some people may work better after a rest, more than making up for time lost. Given the growing popularity of flexitime, it should be possible for some employers to provide siesta time for those who want it. Alternatively, they could simply turn a blind eye to bodies slumped over desks, comforting themselves with the knowledge that errors are being avoided, vital tissues renewed and immune systems strengthened. May the balance sheet confirm this.