Take a break: People who grab a few winks in the afternoon have better productivity

Q. Every day after lunch, you find yourself overcome by drowsiness, and you can’t get any work done because you just want to crawl under your desk and go to sleep. Why does this happen?

A.This universal phenomenon, known as the “post-lunch dip”, represents a collision of biology and economics.

It is entirely natural for humans to want to go to sleep about seven hours after they have awakened. But as the internal rhythms of the body call out for rest, the efficiency of the modern workplace demands continued exertion.

Q.What is happening in the body that it craves rest after lunch?

A.First, the 24-hour cycle of the body, or its circadian rhythm, is naturally in a resting phase at this time. In the afternoon, it happens to converge with another physiological cycle — known as homeostatic — that measures the amount of time spent awake and that is also pushing for a rest.

Add the effects of food, which can also induce drowsiness, and an overpowering desire to sleep may result.

Q.Do all people experience the post-lunch dip?

A.The effect may be natural, but “not everyone experiences it with equal intensity”, said David F. Dinges, a professor and sleep scientist at the University of Pennsylvania School of Medicine.

A few people say they don’t feel the dip at all, while others — about 15 per cent to 20 per cent of the population, he estimates — are “closet nappers”. These are the ones who steal into empty rooms or their parked cars, or fall asleep at their desks, because they can’t fight off the urge to close their eyes.

Often, these people are ashamed of their behaviour because it is associated with laziness, Dinges said. But by giving in to the urge, they are actually improving the quality of their work.

Q.Can being drowsy at work affect productivity and quality?

A.Yes. A study of drivers found that more car accidents occur during the afternoon dip than at noon or 7 pm, Dinges said.

Few studies have been done on drowsiness in the workplace, but it seems likely that more errors in judgment are also occurring in offices, on factory floors and in other work environments at this time.

If possible, workers who are unable to take a nap should try to perform more mundane tasks during the dip, and save projects that require the greatest accuracy, mental acuity and creativity for other times of the day, said Fred W. Turek, a biology professor and director of the Center for Sleep and Circadian Biology at Northwestern University.

Q.If it’s natural to rest in the afternoon, why don’t more companies tolerate napping?

A. A few companies do offer nap rooms as a perk. And in some businesses where safety is paramount, some companies have seen the wisdom of permitting naps, Turek said.

But don’t expect the practice to become widespread. In the end, it is probably more cost-effective to have workers muddle through the two-hour dip in their own individual ways.

In addition, some people need longer naps — sometimes as long as a few hours — to feel refreshed. And longer naps are more likely to lead to what is known as “sleep inertia”, said Phyllis Zee, a neurology professor and director of the Sleep Disorders Center at Northwestern. This is when people remain tired after they wake up and need more time to return to full alertness, she said.

In countries like Spain, where siestas are part of culture and late dinners are the norm, that kind of arrangement may be practical. But allowing an hour for lunch and several hours for nap time is not feasible for most companies.

More realistically, a 20-minute “power nap” can often have a rejuvenating effect, Zee said.

William C. Orr, president of the Lynn Health Science Institute in Oklahoma City and an expert on sleep disorders, said: “It simply isn’t commonly recognised that if individuals are allowed to give in to this natural tendency and take a short nap during the day, then in fact their productivity improves.”

Q.Can a short nap really help?

A.For some people, yes, and the older you are, the less time you need for a nap to be beneficial, Dinges said. But in order to nap effectively, your head must be able to rest on something, he said, like a desk or the back of a chair.

Q.If you can’t take a nap, how can you ease the effect of the post-lunch dip?

A.Many people self-medicate their way through the dip with coffee, Turek said, which helps explain why caffeine is the most-used drug in the world. But responses to caffeine vary, and for some people it can disrupt night-time sleep.

Another way to push through the dip is to exercise or simply get up and move around the room. If you need to talk to a colleague at another desk, this could be the ideal time.

It also helps to wake up at the same time every morning, Dinges said. He has found that getting up earlier than usual — even as little as half an hour earlier — magnifies drowsiness in the afternoon.

Above all, it is important to get a good night’s sleep. With that rest as a backbone, Zee said, “one will naturally begin to feel more alert within a couple of hours” after the dip begins. “Your circadian alerting signal will kick in as the day goes on,” she added, “and it gets higher and higher until about an hour or so before bedtime.”