Scientists think that answering yes to all the above may betray more than a tendency towards slothfulness. Sleep researchers are discovering that there is some biological truth to the adage that people come in “morning” and “evening” types, also called larks and owls.

Among other factors, such as hormonal levels, a set of about 12 genes appear to influence the time you prefer to go to bed. Dr Simon Archer, lecturer in molecular neuroscience at the University of Surrey, has now embarked on a mission to distentangle how these genes work in concert to control our body rhythms.

He has set up a temporary laboratory in the Science Museum in London, where his colleague, Kay Jones, is taking cheek swabs and using questionnaires to gauge the wider connections between sleep preference and genes. The Surrey team hope to rope in a thousand people during Archer’s encampment in SW7.

Such is the range of human “diurnal preference” that extreme larks can be waking as extreme owls slip between the sheets. People are generally good at guessing which bird best describes them, although few people are very strong examples of either.

While filling in the questionnaires has a certain parlour game appeal, the implications of studies into “chronotypes” are very profound. You might, for example, be more or less suited to your particular profession because of it. “It doesn’t make any sense for an evening person to become a milkman or a postman,” Archer says. Likewise, those who prefer to rise with the sun probably wouldn’t make the cheeriest bar workers.

More seriously, fighting a strong biological instinct might carry as yet unknown perils. There is already a growing body of evidence that shift workers are more sickly than those in regular day jobs.

The Surrey team have already discovered the faint bleep of a genetic alarm clock — they found a year ago that individuals at opposite ends of the owl-lark spectrum showed a marked difference in a gene called Period 3. Among very early risers, Period 3 was more likely to come in its longer form, while late risers tended to exhibit the alternative, shorter form.

Archer explains: “We know that the body clock is made up of a dozen genes, and these genes produce proteins that interact in a feedback mechanism. Our hypothesis is that it is the interaction of these genes and proteins that determines differences, and that this changes clock length.” These genes govern the central clock in the brain, the master timepiece by which every cell sets its own time.

Of the thousand people he expects to participate in his experiment, funded by the Wellcome Trust, Archer hopes to uncover a subset of extreme owls and larks. Huge differen-ces are easier to spot than small ones, especially in the encyclopaedic expanse of biological code that constitutes the human genome.

The expectation is that diehard larks will be, genetically speaking, noticeably different from committed owls, and that this will provide a signpost to the link between diurnal preference and genotype. “We’re hoping that once we’ve been though all 12 genes, we can come up with a relationship between genes and cir- cadian rhythms.”

Diurnal preference indeed appears to be a heritable trait. Identical twins, for example, who share 100 per cent of their genes display more similarities in their sleeptime preferences than fraternal twins and siblings, who share 50 per cent.

As a rule, women are more larklike than men, although nobody knows why because the clock genes found so far are not sex-linked. Maturity makes one increasingly larklike; Archer suggests that this could be due to age-related changes in hormone production (eg, melatonin) or a difference in the way genes operate in later life.