Currently your work and life schedules fall mostly into 'day' and 'night', with a few areas breaking up work times into 3 part shifts, morning, evening night etc.

Imagine we live in an artificial enviroment, most likely a space station or world ship, which does not have a sun and light comes from electricity instead; and that this enviroment is far enough away from earth or other planet that it is not ruled by that planets schedules. In this world we don't need to set our schedule by the sun, any time we have as much light as any other time.

How would humans structure their work and daily life in such a structure? Would they still keep a day/night pattern, or would they shift over to something like a 3 shift system where you work shift A, B, or C without any shift being thought of as day or night?

If they kept a shift system how would that impact things like service industry, that usually is only open during the 'day' if there is no official day but insufficient customer volume to justify 24/7 operations? would there be issues with needing something or someone but not being on the right 'shift', basically would every 'shift' be mostly cut off from each other because of when they work and sleep?

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    $\begingroup$ Ask a submariner? $\endgroup$ – Shalvenay Dec 18 '15 at 23:37

I believe that a realistic answer to this will heavily depend on your universe's current understanding of human sleep patterns. Historical records indicate that prior to the easy access to artificial lighting, people used to sleep in two, 4-hour chunks, separated by a waking period of 1-2 hours. A psychiatrist's experiment in the 1990s confirmed this pattern. One study indicated that access to artificial light has shortened our sleep periods by about an hour; seasons also caused variation.

The best long-term case studies that I know of for someone living in a completely artificial light environment occurred over a period between 1962-1972 by the French scientist Michel Siffre. In 1962, he spent two months in a cave, notably without access to a clock or calendar, in an attempt to determine what natural biorhythms would develop in such an environment. In 1972, he repeated the experiment, staying in a cave for six months. [source] For those interested in reading more, the latter experiment was covered in the March 1975 issue of National Geographic in a piece entitled "Six Months Alone in a Cave" (summarized here).

Physiological effects included:

  • developing an extended 25-26 hour sleep/wake cycle, with some occurrences of a 48-hour sleep/wake cycle (36 hours awake, 12-14 hours asleep)
  • a subjective experience of the passage of time; he experienced it ~2x slower than it was in reality (from the 2-month experiment)

There have also been other experiments done as test runs for living in space habitats. The Russian MARS-500 isolation experiment between 2007-2011 simulated a 105-day stage and later a 520-day mission; it's assumed that this closed habitat had no access to natural light. The data on physiological changes is sparse, but articles indicate that circadian rhythms were effected, and that in general, astronauts are plagued by sleep issues.

What do we do with all these facts?

You'd need have some semblance of conformity to a natural sleep cycle unless you want your residents chronically fatigued, irritable, etc. There would be natural limits to wake periods due to physical exhaustion, of course (if we're ignoring biomedical enhancements or pharmaceuticals).

Shift systems might be based on the length of an orbital cycle, if the artificial environment is orbiting a planetary mass. This could be merely for convenience's sake, if the station is coordinating with people working on the planet who are subject to a more traditional day/night cycle.

Material resources are also a consideration; in Neal Stephenson's recent science fiction novel Seveneves, he posited that staggering wake/sleep cycles across a space station's population would prevent a strain on life-support systems and allow it to support a larger population. This did allow for some overlap between people on different "shifts", for work collaboration & social interaction. Special attention was paid to being cognizant & respectful of seeking someone's attention during their sleep period. In your universe, this could be imbued via the development of cultural practices and the implementation of shared calendar/contact systems that warned someone if they were trying to digitally interact with a person who was in a sleep period.

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    $\begingroup$ Now have some sympathy for Alaskans. In the summer, it really is light almost all the time. We stick to roughly the same schedules by convention, but sleep less. :) $\endgroup$ – user11599 Dec 24 '15 at 22:51

I think you mostly answered yourself... even in an artificial environment, forcing people into shifts will cause issues that must be somehow justified. It is not only sunlight or not (we already master electricity to overcome that when we need) but the social life also. People doing unusual shifts often see their lifes altered by that (for example, by having to sleep when their kids are home).

Imagine people living in shifts... how would you schedule, say, an sports event, a legislative meeting, or just a group of friends meeting to have a party together? Forcing people into shifts makes social life harder, so it will be done only when it is absolutely needed (emergency services).

That said, assuming the situation is such that the society is structured around turns, the results won't be as dramatic as your questions point. Nowadays lots of people work in night shifts; when they are required during daytime they just take a day off (usually with a replacement) or make a double turn; human beings have some degree of flexibility. In extreme situations, drugs can be prescribed so a critical individual is kept well aware for an extended time period.


As others have noted, artificial light makes it possible for us to separate ourselves from the natural day-night cycle, but there are still limits to how far we go with this. Most people still live by the natural day. When you're outdoors, sunlight still provides a lot more light than artificial lighting over any large area. (You can light up a stadium with artificial lights, but not a town.) People generally find it more convenient to limit most of their outdoor activity to times when there's plenty of natural light so they can easily see where they're going and what they're doing.

But supposing all we had was artificial light ...

There are pros and cons to living and working in shifts.

The obvious advantage is that you can get better utilization of buildings and machines. Many factories today run 24 hours with 3 shifts. 1 machine running 24 hours a day produces just as much as 3 machines running 8 hours a day. (Well, you have to make some allowance for time for maintenance, etc.) So by running 24 hours the factory cuts its capital investment by 2/3 while getting the same output.

The same principle COULD work in retail. If people worked in 3 shifts, restaurants would only need 1/3 as many tables and chairs, roads would only need to accommodate 1/3 as much traffic, and so on.

As you note, it would be a problem for very small businesses. If the owner of a store is the only clerk, and he wants to work a normal 8 hour day, then he's missing 2/3 of potential business. But for bigger stores it's a non-issue. Instead of having 6 clerks who work the same 8 hours every day, you have 2 for each shift.

Yes, to make it work, people would have to be somewhat more flexible. A company might want to have a staff meeting with all the employees, not just those from one particular shift. Or socially, people might want to have a party with others from different shifts. So people would have to be willing to vary their shifts.

If people tend to work the same shift their whole lives, or at least for very long periods, you might find that society becomes segregated by shift. Someone will find that all his business associates are from the same shift, and maybe even all of his friends. You may find that 2/3 of the population are people you never meet. The different shifts might start to drift apart culturally. Eventually each has its own laws and culture. Etc.

Hmm, I have a sudden thought for a romance novel in this setting: There are huge bureaucratic or cultural barriers to changing shifts, so people divide up into separate cultures based on their shift. One day a man and a woman from two different shifts meet as they pass each other during shift change, or because of some special circumstance. They fall in love, and must struggle to get one of them moved to the other's shift so that they can be together. Their friends can't imagine why they would want to associate with one of "those people" from another shift.

BTW Would people necessarily have three 8-hour shifts? Why not 9 hours or 7 hours? If you're not going by the Sun, who says they have to total 24 hours? Would they have to be distinct? Why not stagger them? Like 8 shifts starting 4 hours apart? Etc.

  • $\begingroup$ since it's usually advised that we sleep 8 hours a night (or 7, or well..no one can decide but 8 seems most common) and we work for 8 hours a day currently 3 shifts seems natural; I work during shift A, play during shift B, sleep during shift C. However, I wasn't committed to it. I could see hours worked per day going down as tech goes up, so perhaps 4 hour shifts, representing the 6 hour of work usually done per day in the future. As to culture, I think people changing jobs to another shift would be common enough to keep culture even. Plus internet shares culture cross-shift. $\endgroup$ – dsollen Dec 17 '15 at 20:45
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    $\begingroup$ See the citation in @zymurge's post: The article says that when people were placed in an environment where they had no exposure to sunlight, no clocks or calendars, and no one to tell them the time of day, so they slept and worked when their bodies felt like it, they shifted to cycles that ranged from 25 to 48 hours. Many years ago I read of similar experiments that had numbers slightly more than 24 hours, though not as high as 48. Of course there could be many factors here. I think if you were doing vigorous physical labor you'd work a shorter day than if you're sitting around ... $\endgroup$ – Jay Dec 18 '15 at 6:51
  • $\begingroup$ ... playing video games, etc. I don't know the details of the experiment, but it's not implausible that if Earth's natural day/night cycle was not a factor, that people might shift away from an 8/8/8 day. $\endgroup$ – Jay Dec 18 '15 at 6:52
  • $\begingroup$ hmm, intresting point to consider. I must admit I would presume our natural body rhythem would still be built for 24 hour days. I can see 25 hour or even 26 at times, but 48 hours seems really long; I would think natural exhaustion would be an issue. I'll look at the study in more detail to figure out it's sample size and validity, but if it holds up then this is a good point and would potentially lead to either 4 shifts, or short 'shifts' where someone may work across two shifts to give more flexibility $\endgroup$ – dsollen Dec 18 '15 at 15:44

There's a great article that I read in National Geographic a few years ago that talks about caffeine and how it has facilitated changes in man's sleep patterns. The gist is that the invention of large scale artificial lighting has enabled man to function outside of the natural daylight cycle. Caffeine has played a large part in allowing humans to function in non-natural patterns.

See: http://ngm.nationalgeographic.com/ngm/0501/feature1/

To tie this into your question, this provides evidence that humans are adaptable to artificial lighting patterns with a little bit of 'chemical assistance'. In a completely artificial environment, the notions of day/night shifts becomes irrelevant. The next challenge would be how adaptable circadian rhythms are. Would our bodies still be tied to a 24 hour cycle or would enough time in a non sun driven setting allow us to adapt our wake/sleep patterns as well?

If we could evolve away from the 24 hour pattern, then believe that schedules would be engineered around functional requirements, such that things would be optimized around the job and less around the people. For instance, in some jobs people might be more efficient in say a 4 hour shift due to the nature of the work and the average person's ability to focus on that type of task. You might create some sort of rhythm with say 4 hours on, 2 hours off, 4 hours on and then say 10 hours off. That turns into a 20 hour day. In the end, maybe that's more optimal.

Whether this can ultimately be done takes me back to the article on caffeine. Prior to the advent of electricity and mass artificial lighting, the external elements weren't in place to allow us to change our patterns. With the lighting and caffeine we proved that we could change into multiple shifts and actually work through night hours. With a further artificial control of the environment and perhaps more regulated caffeine like stimulus, we could evolve to very different patterns than we recognize today.


Analogies (always suspect...)

A: International space station.

B: Any large military ship. While some positions are on deck, what they have to do is not dictated by day/night. And many men won't see daylight for days at a time.

C: Antarctic and arctic bases.

D: Towns, such as Inuvic at higher latitudes than the 23 parallel (extensive periods of either constant dark or constant light.


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