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Our Natural Sleep Cycle

Here's a five-minute TED Talk in which Jessa Gamble talks briefly about how animals (including us) have natural sleep cycles. What happens when you take away a person's watch and shut him in a bunker, deep underground, for a period of months? What is a "natural" sleep cycle for humans, and how does it differ from typical sleep cycles that we practice?

If you enjoyed that tiny tidbit, check out Gamble's book Siesta and the Midnight Sun: How We Measure and Experience Time (currently available only in Canada).

In this tangentially related talk, Arianna Huffington argues for more sleep (including the memorable quote "We've had far too many icebergs hitting our Titanics"):

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Sleeping In on Weekends May Help You Catch Up on Sleep After All
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Weekend mornings are a precious time for nine-to-fivers. If you spend your weekdays staying up long past reasonable bedtime hours and waking up with the Sun, you may be tempted to sleep past noon every day off you get. Sleeping in feels great, and now a new study from sleep scientists at Stockholm University's Stress Research Institute finds that it may also be an effective way to make up for the sleep you missed during the week, contradicting previously held beliefs on the matter.

According to most sleep researchers, the only way to catch up on sleep debt is to adjust your sleeping patterns gradually over time—in other words, cramming in all the sleep you missed last week into a night or two won't cut it. A team of scientists reexamined this theory for their study published in the Journal of Sleep Research [PDF]. Researchers looked at the sleep data from about 44,000 Swedish adults collected in 1997 and followed up with the participants 13 years later. Accounting for factors like age, gender, and education, they report that adults who consistently slept for five hours or fewer throughout the week were more likely to have died after those 13 years than subjects who slept for six or seven hours, seven days a week. Oversleeping every day of the week also put participants at a greater risk of mortality.

But there's good news for people who do all their sleeping in on the weekend—subjects who under-slept five days and slept more during the last two days of the week had no greater risk of death than the people who got healthy amounts of sleep every night of the week. The results call into question past sleep studies that have only looked at sleep patterns during the week, ignoring weekend behaviors. The new study, though, focuses just on the sleeping habits of people at a specific point in time. To confirm what these results suggest, more long-term studies will need to be conducted.

Earlier mortality isn't the only health risk associated with unsatisfactory sleep habits: Getting too little or poor-quality sleep can mess with your memory, appetite, and cognitive and motor performance. That means finding time to get a good night's sleep, no matter the day of the week (if you're lucky enough to have the option), is still the healthiest course of action.

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People With Type A Blood Are More Prone to Severe Diarrhea
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Bad news for people with type A blood who also love to eat at buffets: A new study spotted by Science News reveals that people with this particular blood type have a significantly higher risk of contracting severe diarrhea from a common bacterial pathogen.

Researchers at the Washington University School of Medicine discovered that a protein secreted by a strain of Escherichia coli latches onto sugar molecules that are only found within the blood cells and intestinal lining of people with type A blood.

For the study, 106 healthy volunteers drank water that contained a strain of the bacterium E. coli—one of the major causes of infectious diarrhea around the world. Only 56 percent of volunteers with blood types O and B contracted moderate to severe diarrhea, but 81 percent of volunteers with blood types A or AB fell ill. All participants were later given antibiotics.

Researchers say these findings, which were published in the Journal of Clinical Investigation, could aid the development of an effective vaccine. Developing parts of the world are particularly susceptible to E. coli contamination, which causes millions of infections and hundreds of thousands of deaths each year, researchers note.

As anyone who has ever had "Delhi belly" can attest, this is also a concern for people who travel to developing regions. The main causes of E. coli infection are contaminated food and water, so it's wise to regularly wash your hands and avoid eating raw produce and undercooked beef while traveling.

[h/t Science News]

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