people there report no difference in insomnia between winter, when there are only 3 hours of daylight, or in summer, when there are 21 hours of daylight.

The researchers were surprised because earlier studies have indicated that darkness
during winter might accentuate depression and the sleeplessness that derives from it.

Seasonal Variations in Sleep Problems at Latitude 63°–65° in Norway The Nord-Trøndelag Health Study, 1995–1997 

Most studies on seasonal variability in sleep have asked participants if they think their sleep quality varies with the seasons, which reveals the research hypothesis to the participants. To date, the hypothesis of seasonal variation in sleep has not been tested in a large population-based fully blinded study. The aim of the current study was to investigate monthly variations in sleep problems in a geographic region of Norway with large seasonal differences in daytime light. Using data from a general health survey, the authors had access to information on sleep in the general population, collected across the seasons over 2 years without linking sleep to seasonal variation. In all, 43,045 participants (mean age, 44.6 years) of the Nord-Trøndelag Health Study, 1995–1997 (referred to as “HUNT-2”), provided reports of insomnia symptoms and time in bed in all months except July. The mean prevalence of insomnia symptoms was 12.4%. No evidence of a seasonal variation on reports of insomnia symptoms or time in bed was found. These null findings are in marked contrast to previous seasonality studies of sleep. Previous studies reporting seasonal variations in sleep and insomnia might have been subject to publication biases and lack of blinding to the research hypothesis.

This doesn't mean SAD doesn't exist. But if you can't find seasonal sleep variation in 40,000 people, it probably doesn't exist. If prolonged sunlight during long extreme-north summer days makes it harder to sleep normally, then people must have adjusted (e.g. blinds that actually block the light).

Disclaimer: I play piano.

A new study (abstract here; summary here) argues that musicians have more highly developed brains than the rest of us. The research relates the concept of high mind development to the potential to become really good at something:

New research shows that musicians’ brains are highly developed in a way that makes the musicians alert, interested in learning, disposed to see the whole picture, calm, and playful. The same traits have previously been found among world-class athletes, top-level managers, and individuals who practice transcendental meditation.

Using EEG‘s to measure brain activity, researchers concluded the following about the brains of musicians:

They have well-coordinated frontal lobes. Our frontal lobes are what we use for higher brain functions, such as planning and logical thinking. Another characteristic is that activity at a certain frequency, so-called alpha waves, dominates. Alpha waves occur when the brain puts together details into wholes. Yet another EEG measure shows that individuals with high mind brain development use their brain resources economically. They are alert and ready for action when it is functional to be so, but they are relaxed and adopt a wait-and-see attitude when that is functional.

Musicians also exhibited higher levels of moral reasoning and had more frequent “peak experiences”– intense moments of happiness and feelings of transcending limitations.

Probably the same can be found in anyone who tries hard to do well at a complex task e.g. acting or mathematics (which isn't to say that certain facilities aren't unique in music or sport or politicking, as opposed to purely intellectual pursuits).

Vul and Pashler’s paper on guessing, which I thought would be fun to share; perhaps you missed it initially as I did. Consider this question:

"What percentage of the world’s airports are in the USA?"

The idea is to guess at the answer. Then take a minute, drink a soda or a cup of coffee, and make another guess. The claim is that the average of the two guesses is usually more accurate the original guess. They show by an empirical study that the increase in accuracy is about 6.5 percent. Waiting weeks ups the accuracy much more—the claim is it is now about 16 percent. Here is a chart from their paper:

First, read the graph (bigger bar = more error). The second guess is worse than the first. But the average is better.

It's well known that the average of several experts' estimates is more reliable than a randomly selected expert's.

I'm skeptical about the 3-week delay; if just a few subjects sought out information about the question on the web, then that could explain the difference. However, it makes sense that the first estimate probably anchors the second with immediate re-guessing. Probably the weeks-delayed re-guess is indeed superior even if the person isn't exposed to new information in the interim.

I'd like to compare the average of two quick guesses with one well-considered guess (similar energy expenditure).

(via rjlipton)

p.s. don't use bar graphs if the origin isn't 0; it's misleading

Thanks, Wikipedia.

 An English non-restrictive relative clause is preceded by a pause in speech or a comma in writing, whereas a restrictive clause normally is not. Compare the following sentences, which have two quite different meanings, and correspondingly two clearly distinguished intonation patterns, depending on whether the commas are inserted:

(1) The builder, who erects very fine houses, will make a large profit. (non-restrictive)

(2) The builder who erects very fine houses will make a large profit. (restrictive)

(1) The building company, which erects very fine houses, will make a large profit. (non-restrictive)

(2) The building company that|which erects very fine houses will make a large profit. (restrictive)

Of the two, only which is at all common in non-restrictive clauses.

(apparently Americans favor using "that" where possible - a partial victory for the prescriptivists?)

"When a comma can be inserted, the word is which."^[6] A simple test is to consider whether the clause is essential to the meaning of the sentence and whether removing it significantly changes the meaning of the sentence; if so, usethat. For example:

(1) The pitch that changed the outcome of the game came in the eighth inning.

(2) The fateful pitch, which came on a 2-1 pitch, struck the batter.

and of course,

Jack built the house that I was born in.

Jack built the house I was born in.

("zero relative pronoun")

("that" is also a determiner, e.g. "That dog died.")

This new study (via NY Times) shows that within a year of liposuction, women regained all the weight and fat cells, but distributed elsewhere, since liposuction destroys the substrate under the skin on which fat cells grow.

Background knowledge: fat cells produce hormones that affect hunger and metabolism (resisitin, adiponectin, and leptin). A depleted fat cell "wants" to be filled. Excessively fat people often end up with diabetes and heart failure. They also really experience more physical hunger.

I have 70% belief in the following: if you overfill your fat cells, then the total number of fat cells increases (more or less permanently; they are replaced one for one as they die off). If you boost your peak number of fat cells, you will always have that peak number when you lose weight; they'll just be emptier and causing you more hunger.

Tendencies to "put on weight" first in one location or another are at least partly due to the larger number of fat cells there.

A new theory proposed by the study authors (I don't believe the evidence proves it yet): the body has some homeostasis in terms of the number of fat cells - if you destroy fat cells, it will add more (other than you'd expect from overeating so that existing fat cells are full). If this is true, they should be able to find something produced by each fat cell that doesn't depend on its fullness (as well as the mechanism regulating fat cells birth as a function of that signal). I think this because if the same intensity of hormonal signaling can be caused e.g. by 2 full fat cells as 1 empty one then the liposucked women would be able to avoid growth of new fat cells by leaving those cells empty (which would require a change in their diet). In other words, I'm not sure how the authors ruled out the obvious explanation that the previously fat women continued overeating after the liposuction.

It is interesting at least, to know for sure that there's not much obstacle to putting on a ton of fat anywhere and everywhere - that it's probably not much harder to add 30lbs of fat to just the upper body (assuming full-lower-body-liposuction) than it is to add 30lbs distributed evenly (no liposuction).