Ed Coburn is managing director of Cambridge, Mass.-based Circadian Information, a leading publisher on alertness, performance, health and safety in 24-hour operations. Circadian Information is a division of Circadian Technologies Inc. (CTI). CTI provides consulting, training, research and information services to commercial and governmental organizations with 24-hour operations.
What are circadian rhythms, and how do they affect the body?
"The term 'circadian' means 'about a day.' Circadian rhythms are rhythms that rise and fall during the course of the day in a regular pattern. There are hundreds of bodily functions that operate on these daily rhythms, including hormone production, body temperature, when we sleep and when we digest food. Many of those have the combined effect of impacting our alertness.
"Circadian rhythms are programmed into the human body, causing us to be most alert during the day and to want to be asleep at night. They are the result of millions of years of evolution. They can't be reprogrammed. You can temporarily modify them by taking certain steps, but as soon as you stop taking those steps, you revert back to your natural state.
"There's a common misconception that many people have. Often, a person will think, 'Well, I've been working night shift for 20 years. My body's adapted.' It hasn't adapted, and it can't adapt. This is something people always have to be aware of. Psychologically, you can adapt to the demands, but physiologically, you can't fully adapt."
Physiologically, what is the impact of working at night on the body?
"Our body is designed to shut down at night. Two areas this impacts are our alertness and our digestion.
"There are all kinds of things that conspire against us that reduce our alertness level so that it's easy for us to fall asleep. Because of this, you have to take extraordinary measures to stay alert at night. In addition to the challenge of maintaining alertness overnight, there's a second aspect. This happens when you get home in the early morning and you're trying to go to bed. You're exposed to daylight, and the world is waking up. It's harder to fall asleep, and getting daytime sleep is probably the biggest single issue that you hear from people who work at night.
"Also, our bodies digest food on circadian rhythms. Our bodies have evolved to digest food sometime between 7 and 9 a.m., between 12 and 2 p.m. and between 6 and 8 p.m. for most people. That's why standard mealtimes are when they are. It means that people can't just eat the same meal schedule 12 hours later. Our bodies won't tolerate that. It also means that the foods people choose to eat in the middle of the night have to be different from what they would choose to eat during the day."
What are some things that night shift workers have to do differently?
"Because sleep is issue No. 1 for most shiftworkers, understanding the importance of sleep is essential. It's amazing to me to talk to people who go for years at a time sleeping four or five hours in a 24-hour period. That simply is not enough sleep.
"What is enough varies from person to person. The short answer is that seven and a half to eight hours of sleep is what most people need. The fact is, like everything in human physiology, there is individual variation, and some people simply don't need that much sleep. At the same time, some people need more sleep. Shiftworkers need to understand that sleep is important and must spend time on figuring out a sleep strategy. The human body likes regularity, so if you can try to maintain some kind of regular sleep schedule, both on days when you're working and days off, that will help.
"For example, if you get off at 6 a.m. and you get home and get to sleep between 7 and 8 a.m., you should make an effort on your days off to adjust your schedule so you're not waking up at 6 a.m. Try going to bed at 2 a.m. so you're waking up at 9 or 10 a.m. That way, there are several hours of overlap in the hours you sleep between your days off and your days at work. That sort of thing is important.
"When people are going into a stretch of days off, napping is another option available to them to help them adjust quickly back to a daytime-oriented schedule. They don't want to sleep for six hours, that would throw off their schedule. But if they sleep for a couple of hours, they can take a nap in the middle of the afternoon. When you're figuring out a sleep strategy, make sure to include napping as part of that strategy. I also encourage employers to educate their employees about the importance of sleep and about the use of naps."
What about dietary habits?
"Diet and nutrition is the second major area that people can do something about. We don't digest food well overnight, so you want to avoid greasy foods. You also want to avoid heavy foods like cream sauces, cheeseburgers and pepperoni pizza. Unfortunately, a lot of the prepared food that's available in the night is from fast-food restaurants, which tend to serve foods that should be avoided. Another source of food is vending machines, things like candy bars, soda, potato chips. Those things don't digest as well.
"Candy bars are often positioned as a quick burst of energy, which they are. But once your body has adjusted to the higher energy level, as the sugar effect wears off, your body's energy level actually drops below where it was before. This causes one of two things: it either leaves you feeling temporarily worse than you felt before you had the candy bar, or it makes you crave another candy bar to get back up. It's a double-edged sword.
"Carbonation tends to irritate the stomach somewhat, so you want to minimize the consumption of carbonated sodas. Obviously, some people are going to turn to caffeine in the middle of the night. While coffee and tea have their place, you don't want to consume so much caffeine that it will interfere with your sleep. A shiftworker who gets off work at 6 a.m. would probably want to stop having coffee at 3 a.m. so that by the time he goes to bed at 7 a.m., the caffeine effect has worn off."
What foods do you recommend?
"Things like bagels (but without a lot of toppings like cream cheese), fruits and vegetables, baked potatoes (again the toppings caveat applies) and fruit juices are good. Chicken (preferably skinless) is good, too. If you need a snack food, pretzels are the best choice. Sandwiches can be good, but again, you don't want a big pile of meat and cheese and mayonnaise.
"The general rule about 64 ounces of water a day is even more important for people who work at night. Dehydration increases the effect of fatigue.
"Also, you don't want to eat a lot of food. One thing people often do to help stay alert through the night is munch on things. There is some physiological benefit to this, but the end result is you see a lot of overweight people. You want to moderate your food intake overnight.
"One thing to watch out for, though, is many people will be woken up by hunger prematurely, particularly if they've been eating lightly all night. Sleep is so precious you don't want to get prematurely woken up when it's avoidable. Having a light meal -- a bowl of cereal or a couple of pieces of toast -- would be appropriate."
When employees are on the job, what are the methods for keeping them productive, sharp and alert?
"There are a variety of things you can do to help stay alert. Caffeine is one. In general, I don't need to encourage people to use caffeine; they figure that out on their own. It's important, however, to moderate your caffeine intake.
"Physical activity is also helpful. Unfortunately, there are plenty of overnight jobs that entail sitting around in comfortable chairs monitoring computer screens in dimly lit rooms. That's a setting for sleep if ever there was one. Getting up and walking around, running up and down a flight of stairs or taking breaks is recommended. Doing something active will make a big difference. Some companies with control-room settings have put treadmills or exercise bikes in the control room. If an employee is going to be sitting in a comfortable chair looking at a computer screen waiting for a red light to blink, that employee can just as easily be using a treadmill waiting for a red light to blink.
"Varying tasks also helps. If your job requires four tasks, instead of doing each one for two hours during the course of an eight-hour shift, mix up the tasks. It creates a mental stimulation. Having conversations with other employees provides mental stimulation and keeps you awake, as well. It can help driving, too. That's why I recommend carpooling whenever possible because of that same mental stimulation.
"Listening to a radio is useful. There may be situations where safety dictates that this is not appropriate, but many companies install sound systems that are cut off immediately under certain conditions -- for an announcement or if a general alarm sounds, for example.
"Another thing to check is the lighting level in the work environment. Is it sufficiently high? Most office environments tend to be around 300 lux of light, while outdoors tends to be 10,000 lux and up. At many industrial settings, however, the light hovers around 100 lux. As a result, many industrial settings are very dimly lit, and that tends to promote sleepiness. It's important to get the lighting level up. That being said, there are companies that have spent a lot of money on fancy lighting systems, but they're so bright they produce glare and discomfort for the employees, who often just switch them off.
"Particularly when energy prices increase, companies start removing light fixtures and going from three bulbs to two bulbs or dropping the wattage. That's not a good place for companies to save money. It tends to drop alertness, which can produce accidents and reduce productivity.
"Keeping the temperature at a reasonable level is important. An ideal temperature for people is 65 to 70 degrees. Many people at that level will feel chilly, so it's important to dress in layers and keep a sweater or sweatshirt handy. You want to keep your head and neck at that temperature, but the rest of your body can be warmer if you like."
Are there times during a night shift when accidents and errors are more likely to occur?
"Absolutely. For most people, it's going to be sometime between 4 and 6 a.m. Some time in that range most people reach the lowest point in their body temperature cycle, and that's when our alertness is at its absolute lowest. In general, the accident rate is higher overnight, but accidents cluster around this time. That's a particularly important time to be physically active and to take some of these countermeasures."
What is the best way to design a work schedule?
"There are plenty of work schedules that aren't biocompatible. They require people to work a schedule that virtually guarantees that they're not going to be able to get enough sleep and that will disrupt their circadian rhythms much more than is necessary.
"If it's a rotating schedule, our bodies adapt better physiologically to rotating forward. Going from a day shift to an evening shift to a night shift is easier for most people. If companies don't understand the physiology of it, more often than not they actually rotate backwards because it gives employees an additional 16 hours off, as opposed to a string of shifts rotating forward. But I don't think that's a worthwhile trade-off.
"Unfortunately, there is no one, perfect schedule. What makes a schedule work in one setting may prohibit it from working in another setting. It depends on the composition of the work force and local customs, the nature of the work and labor relations issues, and often just individual personal preferences. Some people prefer eight-hour shifts, while others swear by 12-hour shifts or rotating or fixed. There are hundreds of different schedules. What's important is to be sure a company has a schedule that works well and that employees like."
What are the trends in shiftwork?
"Napping at the work site is a controversial topic. Some companies won't even discuss it. Where it's appropriate, it's great that companies have started to permit napping at work during breaks. Even if you don't permit it at work, train people about its benefits. If they're coming off a night shift, they're tired and they have a 45-minute commute, they would know they ought to take a 15-minute nap before they get behind the wheel.
"Some companies have developed napping policies and have provided napping facilities. It's a nascent trend right now. It's something that first takes management buy-in. Management needs to understand the sleep issue that's confronting employees and then understand that napping can be a very important part of that. Companies long ago accepted that having free coffee available means you get a lot more productivity out of your employees all morning long. That's something that no one would question. Napping is not that dissimilar; it's just not in the same frame of mind for most people.
"Another trend is the increase in health promotion and wellness training that corporations are doing. Corporations are looking at things not only from a health and safety perspective, but also from a quality of life perspective. Training employees about circadian rhythms is one area these programs could potentially address. You don't need to make your employees sleep experts, but you need to give them some idea why working at night is different from working during the day. A lot of people are under the misconception that it's just a darker version of working during the day, and it's not. Physiologically, it's very different. People need to accept that or else everything else doesn't sink in to them."