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Can You Catch Up On Sleep?

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When we pull an all-nighter to study for a test or put together a presentation, we assure ourselves we’ll just make it up later—but can you really catch up on lost sleep?

The amount of sleep needed varies by person, but the National Sleep Foundation has settled on 7 to 9 hours a night. One-third of Americans aren’t even reaching the low number of that scale, and those who sleep less than 7 hours a night, on average, are considered sleep deprived. Unfortunately for them (or us), that sleep debt builds up … and it never quite goes away.

If you’ve lost more than five hours of sleep this week, or it’s been more than a few days since that sleepless night, you may as well cut your losses—gaining that sleep back is scientifically unlikely. Dr. Raghu Reddy, pulmonologist at the University of Arkansas for Medical Sciences and a sleep medicine specialist, says the body can recover up to five hours of lost sleep; beyond that, the body has to scramble to adjust to the sleep deprivation, sometimes by skipping straight to the REM stage of sleep instead of wasting time in less-beneficial stages. Short-term sleep recovery is supported by Martha Jefferson Hospital Sleep Medicine Center’s medical director Dr. Christopher Winter as well, who says that “recovery sleep in the short term does work,” but never specifies a duration for that short-term span.

Not that they encourage people to use those facts as an excuse to neglect sleep. A study published by the American Physiological Society show that sleep-deprived people didn’t improve on attention tests even after a period of recovery sleep. The test mimicked a normal week: six hours of sleep for six nights, followed by three nights with ten hours of sleep, and showed that that pattern doesn't negate the effects of sleep loss. A 2003 Walter Reed Institute of Research study corroborated this failure to recuperate brain performance with extra sleep; researchers said that “the brain adapts to chronic sleep restriction” and performs “at a reduced level” for days—or maybe even longer—after the sleep has been recovered.

Not only does it take longer than a few days to get back to normal after missing sleep; your sleep debt actually accumulates, and switching up your sleep patterns can throw off your ability to recover. UT Southwestern Medical Center’s sleep medicine specialist cautions against sleeping at different times every night, which would delay one’s circadian clock; instead, fall asleep eight hours before waking up for best sleep-recovery results. Lawrence Epstein, medical director of Sleep HealthCenters, advises months of regular sleep patterns to erase your sleep debt, and the previously-mentioned Dr. Reddy encourages “good sleep hygiene,” including relaxing routines before bed, avoiding stimulating activities or beverages (coffee, for example, and alcohol), and keeping strict times for sleeping and waking in order to keep your circadian clock happy.

Sleep is commonly sacrificed in favor of productivity or a fun night out, but sleep deprivation can lead to problems like declined memory retention, obesity, and early death. The good news, though, is that there are studies suggesting you can bank sleep in advance of snooze-less nights in order to counteract the sleep deprivation, which is helpful if you plan your sleep schedule carefully.

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Big Questions
How Does Autopilot Work on an Airplane?
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How does autopilot work on an airplane?

Joe Shelton:

David Micklewhyte’s answer is a good one. There are essentially a few types of features that different autopilots have. Some autopilots only have some of these features, while the more powerful autopilots do it all.

  • Heading Hold: There’s a small indicator that the pilot can set on the desired heading and the airplane will fly that heading. This feature doesn’t take the need for wind correction to desired routing into account; that’s left to the pilot.
  • Heading and Navigation: In addition to holding a heading, this version will take an electronic navigation input (e.g. GPS or VOR) and will follow (fly) that navigation reference. It’s sort of like an automated car in that it follows the navigator’s input and the pilot monitors.
  • Altitude Hold: Again, in addition to the above, a desired altitude can be set and the aircraft will fly at that altitude. Some autopilots have the capability for the pilot to select a desired altitude and a climb or descent rate and the aircraft will automatically climb or descend to that altitude and then hold the altitude.
  • Instrument Approaches: Autopilots with this capability will fly preprogrammed instrument approaches to the point where the pilot either takes control and lands or has the autopilot execute a missed approach.

The autopilot is a powerful computer that takes input from either the pilot or a navigation device and essentially does what it is told to do. GPS navigators, for example, can have a full flight plan entered from departure to destination, and the autopilot will follow the navigator’s guidance.

These are the majority of the controls on the autopilot installed in my airplane:

HDG Knob = Heading knob (Used to set the desired heading)

AP = Autopilot (Pressing this turns the autopilot on)

FD = Flight Director (A form of navigational display that the pilot uses)

HDG = Heading (Tells the autopilot to fly the heading set by the Heading Knob)

NAV = Tells the autopilot to follow the input from the selected navigator

APR = Tells the autopilot to fly the chosen approach

ALT = Tells the autopilot to manage the altitude, controlled by the following:

VS = Vertical Speed (Tells the autopilot to climb or descend at the chosen rate)

Nose UP / Nose DN = Sets the climb/descent rate in feet per minute

FLC = Flight Level Change (An easy manual way to set the autopilot)

ALT Knob = Used to enter the desired altitude

This post originally appeared on Quora. Click here to view.

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Big Questions
What's the Difference Between Vanilla and French Vanilla Ice Cream?
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While you’re browsing the ice cream aisle, you may find yourself wondering, “What’s so French about French vanilla?” The name may sound a little fancier than just plain ol’ “vanilla,” but it has nothing to do with the origin of the vanilla itself. (Vanilla is a tropical plant that grows near the equator.)

The difference comes down to eggs, as The Kitchn explains. You may have already noticed that French vanilla ice cream tends to have a slightly yellow coloring, while plain vanilla ice cream is more white. That’s because the base of French vanilla ice cream has egg yolks added to it.

The eggs give French vanilla ice cream both a smoother consistency and that subtle yellow color. The taste is a little richer and a little more complex than a regular vanilla, which is made with just milk and cream and is sometimes called “Philadelphia-style vanilla” ice cream.

In an interview with NPR’s All Things Considered in 2010—when Baskin-Robbins decided to eliminate French Vanilla from its ice cream lineup—ice cream industry consultant Bruce Tharp noted that French vanilla ice cream may date back to at least colonial times, when Thomas Jefferson and George Washington both used ice cream recipes that included egg yolks.

Jefferson likely acquired his taste for ice cream during the time he spent in France, and served it to his White House guests several times. His family’s ice cream recipe—which calls for six egg yolks per quart of cream—seems to have originated with his French butler.

But everyone already knew to trust the French with their dairy products, right?

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