Analyze This: Sleep patterns vary widely across the world | Science News for Students

Analyze This: Sleep patterns vary widely across the world

Keeping a consistent sleep schedule is part of getting a good night’s sleep
May 24, 2017 — 6:50 am EST
waking up

Getting a good night’s snooze is important, but what that looks like can vary greatly between cultures.

diego_cervo/iStockphoto

Sleep is important. When someone doesn’t get enough zzzzz’s, it becomes harder for them to learn new things, pay attention to their surroundings and concentrate on schoolwork. With too little sleep, people tend to be more inclined to choose unhealthy foods. Behind the wheel of a car, they might even make unsafe moves.

But what’s the most important aspect of sleep? Is it the quality of shuteye, the amount of dream time or a consistent sleep schedule (each day going to bed and rising at about the same time)? The answer is all of the above. In fact, recent data suggest that keeping a consistent sleep schedule might be every bit as important as getting the right amount of quality sleep.

Interestingly, not everyone in the world keeps to the same types of sleep schedules. In a pair of recent studies, scientists looked at the sleep patterns of four groups of people. The Hadza are hunter-gatherers that live in Tanzania, a nation in East Africa. The Malagasy live in villages on the large island nation of Madagascar, off Africa’s lower East Coast. Both groups live without electricity. These people were compared to those living in the West (places like the United States and Europe) as well habits in Western Europeans who lived before the Industrial Revolution, some 200 to 500 years ago.

sleep graph
The yellow areas in this graph show typical sleep times for four groups of people: the Hadza, preindustrial Western Europeans, present-day Westerners with 9-to-5 jobs and villagers in Madagascar who live without electricity. Sleep patterns are not constant across all cultures, scientists contend. Instead, they are shaped by local environments and the ways in which groups live.
D. SAMSON ET AL/AJPA 2017

On average, modern-day adults in Western nations sleep around 7 hours each night. Both the Malagasy and Hadza adults sleep slightly less than that, on average. This might be, in part, because the non-Western villagers spend more of their days in natural sunlight. Also, they are exposed to less blue light (from indoor lighting and computer screens), which can confuse the body’s internal clock. Napping once or twice a day may also have some effect. Hadza adults average 47.5 minutes of daily napping; Malagasy villagers, on average, nap 7.5 minutes more than that each day. Naps were usually taken during the hottest hours of the day.

Except for the naps, the Malagasy villagers’ sleep pattern is very similar to that of preindustrial Western Europeans. In both cases, adults went to sleep a little after 6 p.m. Then they slept in two shifts. The first shift ended around midnight. Then, after remaining up for an hour or so, they would fall back to sleep again.

By comparison, present-day Westerners (such as adults working 9 to 5 jobs in the United States) typically go to sleep just before midnight and get up around 6 a.m. And no mid-day naps for the majority of them!


Data Dive: 

The National Sleep Foundation recommends that children from the ages of six to 13 get nine to 11 hours of sleep each night. The recommendation for teens from 14 to 17 years old is eight to 10 hours of shuteye each night. How much sleep do you think you get per night on average? How does this compare with the recommendations for your age group?

Now, let’s gather some data! Record when you go to sleep and how much sleep you get each night for a week. On average, is this more or less sleep than you thought you were getting? How consistent is your sleep schedule? Did it change on the weekend? How might this change if you tracked your sleep for a month?

Think about the adults that you know. Do you think that their sleep schedule is similar to the “present day Westerners” in the graph above? Can you think of other situations, jobs or schedules that would change someone’s sleep schedule?

How could this graph be improved? Is there another way to graph these data?


Analyze This! explores science through data, graphs, visualizations and more. Have a comment or a suggestion for a future post? Send an email to sns@sciencenews.org.


Power Words

(for more about Power Words, click here)

average     (in science) A term for the arithmetic mean, which is the sum of a group of numbers that is then divided by the size of the group.

body clock     (also known as biological clock ) A mechanism present in all life forms that controls when various functions such as metabolic signals, sleep cycles or photosynthesis should occur.

culture     (n. in social science) The sum total of typical behaviors and social practices of a related group of people (such as a tribe or nation). Their culture includes their beliefs, values and the symbols that they accept and/or use. Culture is passed on from generation to generation through learning.

data     Facts and/or statistics collected together for analysis but not necessarily organized in a way that gives them meaning. For digital information (the type stored by computers), those data typically are numbers stored in a binary code, portrayed as strings of zeros and ones.

environment     The sum of all of the things that exist around some organism or the process and the condition those things create. Environment may refer to the weather and ecosystem in which some animal lives, or, perhaps, the temperature and humidity (or even the placement of components in some electronics system or product).

hunter-gatherer     A cultural group that feeds itself through hunting, fishing and gathering wild produce (such as nuts, seeds, fruits, leaves, roots and other edible plant parts). They can be somewhat nomadic and do not rely on agriculture for their foods.

Industrial Revolution     A period of time around 1750 that was marked by new manufacturing processes and a switch from wood to coal and other fossil fuels as a main source of energy.

link     A connection between two people or things.

preindustrial     An adjective that refers to the period before societies had begun to industrialize, using machines and fossil fuels to build products, often with assembly lines or big teams of workers. In the United States, that period began in the mid- to late-1700s.

Western     (n. the West)  An adjective describing nations in Western Europe and North America (from Mexico northward). These nations tend to be fairly industrialized and to share generally similar lifestyles; levels of economic development (incomes); and attitudes toward work, education, social issues and government.

Further Reading

Source Story (Science News):  Snooze patterns vary across cultures, opening eyes to evolution of sleep

Journal: D. Samson et al. Hadza sleep biology: Evidence for flexible sleep-wake patterns in hunter-gatherersAmerican Journal of Physical Anthropology. Vol. 162, March 2017, p. 573. doi:10.1002/ajpa.23160.  

Journal: D. Samson et al. Segmented sleep in a non-electric, small-scale agricultural society in MadagascarAmerican Journal of Human Biology, published online February 9, 2017. doi: 10.1002/ajhb.22979