6 ms·

Night owls have more mental stamina than those who awaken at the crack of dawn

81 points by soundsop 17y ago

awolf 17y ago
"After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls." Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls. 10 hours is a pretty long period of time to stay focused. Instead they should compare the mental efficiency of the two groups over a two hour period of focused work.
- pygy 17y ago
  > but this study says nothing about the quality or intensity of the early birds vs. night owls. Yes it does. Sleep length was fixed at 8 hours, and they acquired polysomnographic recordings of both nights spent at the lab and scored the sleep quality. ==> No statistical difference. They controlled most controllable parameters. Read the paper and the supporting materials.
- potatolicious 17y ago
  > "Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls." No offense, but that sounds like rationalizing the result to maintain your own current prejudices as opposed to a genuine criticism of the research.
inovica 17y ago
I've done both - spent time working early mornings and also into the night. I found that working early in the morning I'm more productive per hour than I am at night. I find nighttime working to be more creative though. The mornings are good for me "getting things done" and by 9-10am all the planned work I had was done
- Maktab 17y ago
  My experience mirrors this. I get through a lot more work and admin in a given day if I work from 7am-4pm, especially if there's a lot of drudgery involved. In contrast, if I work from 9am-6pm or later I'm more likely to procrastinate but I get a spurt of creativity that starts in the late afternoon and gets amplified at night. So I try to structure my work day around that, using early mornings to race through necessary but boring work and to tie up the remaining loose ends from the day or night before while leaving particularly challenging problems for later in the day or the evening. Not to mention that the feeling of getting a bunch of tasks out of your way early in the morning usually acts as a potent motivator for the rest of the day.
- deleted 17y ago
  [deleted]
- 9oliYQjP 17y ago
  I'm not a morning person, but my experience is similar to yours. What I settled on when circumstances allow for it is to wake up early in the morning to get non-creative stuff done. Then, I have a nap for maybe 2 hours. Following this nap, I continue on with my day, first taking care of the new work generated by my first round of morning work, before settling in on the meat of what I do when most people are winding up for the day.
- tdavis 17y ago
  I'm the same way (and I used to hate morning). I'm not sure if it's a product of it being quieter in the early morning when I first wake up (as opposed to at noon), the fact that recently I've been alone in the "office" for most of the day, or what, but I definitely find it easier to get into "the zone" in the morning and get a lot of work done. I'm writing code 8-12 hours a day now, which is pretty outstanding considering it isn't a new project or something. The fact that I'm exhausted by about 8pm doesn't really bother me.
jacquesm 17y ago
The only reasons I can come up with for pulling an all nighter is that a deadline is near and that it is much more quiet at night. "Increased Mental Stamina" is a metric I'm not familiar with, is that how many pushups your brain can do ? Mind you, I'm one of those 'night owls', but this quote from TFA is very funny: "Maintaining their natural schedules, the volunteers spent two consecutive nights in sleep labs. After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls. The early risers also felt sleepier and tended to perform tasks more slowly, compared with the night owls, when their level of alertness was measured." So, the night owls get to maintain their natural rhythms and spend their nights in a sleep lab and so did the early risers ? But for the night owls that makes the situation totally different than for the early risers, after all, the early risers are going to be quite tired by that time and they'd like to sleep, but being in a different environment they can't or will not sleep as good as they normally would. The nightowls just hang out, go home and sleep it off... Or am I missing something here ?
fauigerzigerk 17y ago
I keep wondering what makes researchers doing that kind of work so confident that they have captured all the relevant variables. It may well be that being a night owl is not just genetic but acquired by people who are unusually motivated to stay alert for longer times. Don't we all know the feeling of not wanting to stop?
- HoneyAndSilicon 17y ago
  Well, in my experience, the average behavioral researcher isn't so much "confident they have captured all the relevant variables"... as "confident they have a research paradigm that will yield publishable data." —from a recovering academic As for "Don't we all know the feeling of not wanting to stop?"... maybe us on HN. But your comment raises a significant issue: those who do readily get into that "not wanting to stop" place are likely to end up working late because of that engagement (and hence focus).
- sophacles 17y ago
  That feeling of not wanting to stop, while responsible for most of my noteworthy accomplishments, scares a lot of people. I have had several people who have tried to "fix" me because they decided that me being up most of hte night finishing something was unhealthy. They never seem to understand the idea of ramp up time, nor do they seem to understand the fickle mistress inspiration. There was one guy, a kind of mentor to me, who tried to tell me it was a moral imperitive to get up early and get to work, to show the bosses I cared. For some reason staying late didn't show the same thing, particularly if i took advantage of the flex time and showed up around noon. Fortunately this guy was not my boss, and instead I get to be productive in the way that fits me best. Fortunately this guy broke off the mentorship after I got promoted in spite of my "terrible scheduling habits".
- req2 17y ago
  It's easier to observe and control for the sleep schedule and then measure alertness, rather than the other way around.
embeddedradical 17y ago
although this may be true, the study is quite superficial. personally, my issue with sleep has been that if you leave me alone in a dark room (like in my bed), i'll come up with all sorts of ideas... also, distractions taper off as the night progresses, and i'll be like 'k, this feature, then done' - but then you realize you need another feature but you have all this information in your head you need to get out -- and the details keep piling in. if you were to jot down notes, you might as well have coded it and tried it out.... and then you realize something else you can do. other nights, you go ah, this is nice, and just know what the next step is and as long as it's somewhat concrete, it's easy to sleep knowing you'll do it tomorrow. generally, i find it easier to sleep if i've hit one of these plateaus, or if i'm stuck, or if there's too many options of where to go from here; the answer will be clearer tomorrow. It's when the answer is -almost- clear, just need to try out a few things, that sleeping feels like trying to swim upstream. i've tried to 'fix' my sleep so many times in life now, by which i mean be consistent - and so far, no success. nothing too bad has happened to me, either -- if i don't get enough sleep i know i'm sub-par but i feel capable of at least being 'average' until i get home and get more sleep the next night. on the other hand, i've taken vacation simply because i know if i don't solve this ranking algorithm, i'm going to go insane - so i took three days off (wed-fri, so i got weekend too), and worked through the day and night, sleeping as fit until it was all good, and that itch in my head was resolved.
billswift 17y ago
The claims in the article, including those specifically attributed to the researchers, go far beyond anything justifiable by the research. The "genetics" claim is especially unjustified. Personally, I can and have slept and worked ANY schedule, as long as I can get enough sleep. Creative work or intense studying though work best with a split schedule, where I have two 3-5 hour sleeping shifts, so I am always fairly fresh.
- pygy 17y ago
  The genetic origin of the variation in circadian phenotypes are well documented, and have been for a long time. You can work against your predispositions, but if you remove social constraints, your natural pattern will quickly re-emerge. Furthermore, your subjective assessment of your productivity along the day is not really meaningful in this context.
  - Goladus 17y ago
    Smug early birds take note: Night owls actually have more mental stamina than those who awaken at the crack of dawn, according to new research. "It's the late risers who have the advantage, and can outperform the early birds," said Philippe Peigneux He's not actually talking about "performance" in a general, life-applicable sort of way; rather he is talking about performance at specific mental tasks. You wouldn't think that from the way the article is written, however.
Mistone 17y ago
working my regular job and doing a side startup has def made me embrace the night-owl shift. I find that my first hour of night work, say 9-10, is less productive then I'm able to pick up the pace from 10-1, at that point I have to go to sleep or I'm wrecked the next day. Ideally, when I'm able to go 100% on the startup, I would work from 8:30-5:30, come home chill with the fam, then work 9ish-1ish. that way I get 6 hours sleep, have time to hang with kids and still put in a solid 12-13 hours. funny that my dream is to be able to work 13 hours a day, but its really about doing something I love and own, and the crazy hours are a side result.
- rokhayakebe 17y ago
  If you have a startup and a day job I urge you to secretly work on your startup as much as you can while at your day job. This is wrong, but gotta do what you have to do to do what you want to do.
pygy 17y ago
Here we go again... People with nothing but their own anecdotal experience about the subject trying to (and failing at) criticizing a scientific paper. No one has pulled off a "correlation != causation", but most other usual suspects are already there. Disclaimer: 1) I work in neuroscience , but not in sleep research. This (hopefully) makes me qualified to assess the seriousness of the methods, even though I don't have much background in circadian rhythms. 2) I'm biased in this case since I know personally the first author of the paper and some of the other researchers involved (and they are among the smartest and more conscientious people that I know of). If there were any methodology error lay people would be able to spot in the paper, it wouldn't have been published in any respected journal in the field (and most people who commented here are lay people regarding (sleep) science). This is Science Magazine... They have the best reviewers in the world ("best" as in "smarter than you can probably imagine"). There are shortcomings inherent to this kind of study, of course. You cannot control experimental parameters like you can in physics or chemistry. That's why you have to 1) build your research on solid ground (i.e. solid results already published and reproduced) and 2) be as careful as possible in designing your protocol in order to have your bases covered. Schmidt et al. used the gold standard, they're frankly out of reach of such "low hanging" criticism. </rant> I enjoin you to have a look at the paper and the supporting material. _ Full text: http://www.innovatieforganiseren.nl/wp-content/uploads/2009/04/516.pdf http://www.innovatieforganiseren.nl/wp-content/uploads/2009/... Supporting Online Material: http://www.sciencemag.org/cgi/data/324/5926/516/DC1/1 http://www.sciencemag.org/cgi/data/324/5926/516/DC1/1 _ Here's the beginning of the latter: _ 1. Material and methods Subjects. [Ethical committee disclaimer]. [All subjects] were screened for morningness or eveningness according to their timing preferences as defined by two questionnaires (MEQ (1) and MCTQ (2)). The two groups were matched according to age, sex and educational level and did not differ in their anxiety and depression levels as well as in sleep quality and day time sleepiness (all ps > 0.1; Table S1). Morning and evening types significantly differed in their scores on the two chronotype questionnaires (MEQ and MCTQ). Exclusion criteria were reports of medical, psychiatric and sleep disorders, medication or drug consumption, alcohol abuse, excessive caffeine consumption or physical activity, shift work within the three past months, and transmeridian travel or disturbances in the sleep-wake cycle within one month before the experiment. Design and Procedures. An overview of the study design is illustrated in Fig. 1 of the main text. Individual times were scheduled according to each volunteer’s preferred sleep and wake timing. Criteria for such timing preferences included sleep schedules adopted on free days as assessed by the MCTQ (2) and after interviewing the subject to ensure that the scheduled timing was as close as possible to the schedule that he or she would spontaneously adopt. In a second step, the screened subjects came to the sleep facility for a habituation night. After this night, they were asked to follow the sleep schedule (± 30 minutes) they would spontaneously adopt while free from any social and professional constraints. Target bedtimes and wake times were determined for a sleep duration of about 8 h (± 30 minutes). To assess the subjects’ compliance to the selected rest-activity patterns, motor activity of the non-dominant arm was recorded using actimeters the week prior to the experimental sessions along with sleep-wake logs. After this week under actimetry recording, subjects came to the sleep laboratory for 2 consecutive nights. The precise schedule of each session was individually adapted according to the subject’s habitual bedtime on the basis of the mean timing of the subject’s sleep midpoint derived from actimetric data of the preceding week. Subjects reported to the laboratory 7 hours before habitual lights off on day 1. After the hook-up of the electrodes, they continuously stayed under controlled conditions in dim light (< 10 lux) in order to avoid the influence of bright light on circadian rhythmicity parameters (3) and in the aim to equalize pre-scan conditions between subjects. Subjective sleepiness (Visual Analogue Scale (VAS) and Karolinska Sleepiness Scale (KSS (4))) and objective vigilance (a modified version of the PVT (5)) were assessed at hourly intervals while awake. Furthermore, hourly collected saliva samples were assayed for melatonin using a direct double-antibody radioimmunoassay validated by gas chromatography-mass spectroscopy with an analytical at least detectable dose of 0.65 pg/ml (6). Circadian phase was estimated by the calculation of the mid-range crossing time of salivary melatonin (7, 8). For each individual curve, the maximum value and the minimum value was averaged (mid-range value pg/ml) and taken to determine the mid-range crossing time (time of day, h) on the abscissa. Polygraphic data (see below) were recorded during the nights preceding fMRI sessions. After lights off, subjects were allowed to sleep for 8 hours. Then, 1.5 (morning session) and 10.5 (evening session) hours after wake up of scheduled sleep timing, they underwent a fMRI session during the practice of various cognitive tests, including the psychomotor vigilance task on which we focus here. For half of the subjects, the morning session followed the first experimental night and the evening session the second night, whereas for the other half of the volunteers the morning session followed the second experimental night and the evening session the first night. Subjects were allowed to leave the facility between the two experimental nights. They stayed in the laboratory under dim light conditions (<10 lux) for at least 4 hours before the scanning sessions (see dashed line in Fig. 1). They wore protective glasses avoiding excessive light input when going to the scanner room. The order of selected cognitive tasks was counterbalanced across subjects and sessions. Before the start of the experimental protocol, all subjects underwent a short habituation scan session in order to familiarize them with the noise and the body positions associated with the fMRI environment.
ivankirigin 17y ago
Intensity and focus matter more than stamina. The stamina that matters is over the course of months or years.
scotch_drinker 17y ago
Aren't we just comparing apples and oranges here? Is it really that counterintuitive that people who get up at 5 AM tend to not be terribly mentally acute at 3 PM? Is it counterintuitive that night owls would be more mentally acute later in the day? Let's see a study that measures the mental acuity of extreme morning people at 7AM and the mental acuity of extreme late risers at 2 PM. Better yet, let's measure mental acuity of the two groups immediately upon waking. Surely that must be just as significant as the study above. Studying the mental performance of two groups when one group is seriously disadvantaged (and if you think people who get up at 5 AM aren't disadvantaged at 3 PM, I think you're not being honest) isn't particularly note-worthy if you ask me.
- pygy 17y ago
  The measurements were performed at time points relative to the natural rhythms of the subjects i.e. respectively 1h30 and 10h30 after waking up according to their natural rhythms. Have a look the methods and protocol linked above.
  - scotch_drinker 17y ago
    That's not what the article says. The article seems to draw its conclusions entirely on this statement: "After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls." I saw from your comments above that measurements were taken at two different times. However, the article, not the study, is linked prominently on the front page of HN and that's what I'm taking exception with. I have no doubt that the study is rigorous and careful but the conclusions drawn and the tone taken by the author of the article are sketchy at best. On top of that, as you mention in a previous comment, the study is comparing what the two groups can do in "their relative evenings". Again, this seems like apples to oranges to me. Of course morning people are going to be less effective in their evenings because, well, they are MORNING people. I guess I would be interested in understanding what we hope to get from a study like this. The article says people who are extreme in either direction are genetically predisposed to their own personal direction. If we identify that one group of people is better than the other based on their genetics, what does this do for us, long term? That's something I'd be interested in hearing about.
biohacker42 17y ago
Why does this cheeky crap article have 52 freaking points? Oh sorry I'm supposed to flag and shut up, not complain.
- Goladus 17y ago
  The research is interesting, despite the crappiness of the article.

81 points by soundsop 17y ago

awolf 17y ago

"After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls." Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls. 10 hours is a pretty long period of time to stay focused. Instead they should compare the mental efficiency of the two groups over a two hour period of focused work.

pygy 17y ago
> but this study says nothing about the quality or intensity of the early birds vs. night owls. Yes it does. Sleep length was fixed at 8 hours, and they acquired polysomnographic recordings of both nights spent at the lab and scored the sleep quality. ==> No statistical difference. They controlled most controllable parameters. Read the paper and the supporting materials.
potatolicious 17y ago
> "Yah fine... but this study says nothing about the quality or intensity of the early birds vs. night owls." No offense, but that sounds like rationalizing the result to maintain your own current prejudices as opposed to a genuine criticism of the research.

inovica 17y ago

I've done both - spent time working early mornings and also into the night. I found that working early in the morning I'm more productive per hour than I am at night. I find nighttime working to be more creative though. The mornings are good for me "getting things done" and by 9-10am all the planned work I had was done

Maktab 17y ago
My experience mirrors this. I get through a lot more work and admin in a given day if I work from 7am-4pm, especially if there's a lot of drudgery involved. In contrast, if I work from 9am-6pm or later I'm more likely to procrastinate but I get a spurt of creativity that starts in the late afternoon and gets amplified at night. So I try to structure my work day around that, using early mornings to race through necessary but boring work and to tie up the remaining loose ends from the day or night before while leaving particularly challenging problems for later in the day or the evening. Not to mention that the feeling of getting a bunch of tasks out of your way early in the morning usually acts as a potent motivator for the rest of the day.
deleted 17y ago
[deleted]
9oliYQjP 17y ago
I'm not a morning person, but my experience is similar to yours. What I settled on when circumstances allow for it is to wake up early in the morning to get non-creative stuff done. Then, I have a nap for maybe 2 hours. Following this nap, I continue on with my day, first taking care of the new work generated by my first round of morning work, before settling in on the meat of what I do when most people are winding up for the day.
tdavis 17y ago
I'm the same way (and I used to hate morning). I'm not sure if it's a product of it being quieter in the early morning when I first wake up (as opposed to at noon), the fact that recently I've been alone in the "office" for most of the day, or what, but I definitely find it easier to get into "the zone" in the morning and get a lot of work done. I'm writing code 8-12 hours a day now, which is pretty outstanding considering it isn't a new project or something. The fact that I'm exhausted by about 8pm doesn't really bother me.

jacquesm 17y ago

The only reasons I can come up with for pulling an all nighter is that a deadline is near and that it is much more quiet at night. "Increased Mental Stamina" is a metric I'm not familiar with, is that how many pushups your brain can do ? Mind you, I'm one of those 'night owls', but this quote from TFA is very funny: "Maintaining their natural schedules, the volunteers spent two consecutive nights in sleep labs. After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls. The early risers also felt sleepier and tended to perform tasks more slowly, compared with the night owls, when their level of alertness was measured." So, the night owls get to maintain their natural rhythms and spend their nights in a sleep lab and so did the early risers ? But for the night owls that makes the situation totally different than for the early risers, after all, the early risers are going to be quite tired by that time and they'd like to sleep, but being in a different environment they can't or will not sleep as good as they normally would. The nightowls just hang out, go home and sleep it off... Or am I missing something here ?

fauigerzigerk 17y ago

I keep wondering what makes researchers doing that kind of work so confident that they have captured all the relevant variables. It may well be that being a night owl is not just genetic but acquired by people who are unusually motivated to stay alert for longer times. Don't we all know the feeling of not wanting to stop?

HoneyAndSilicon 17y ago
Well, in my experience, the average behavioral researcher isn't so much "confident they have captured all the relevant variables"... as "confident they have a research paradigm that will yield publishable data." —from a recovering academic As for "Don't we all know the feeling of not wanting to stop?"... maybe us on HN. But your comment raises a significant issue: those who do readily get into that "not wanting to stop" place are likely to end up working late because of that engagement (and hence focus).
sophacles 17y ago
That feeling of not wanting to stop, while responsible for most of my noteworthy accomplishments, scares a lot of people. I have had several people who have tried to "fix" me because they decided that me being up most of hte night finishing something was unhealthy. They never seem to understand the idea of ramp up time, nor do they seem to understand the fickle mistress inspiration. There was one guy, a kind of mentor to me, who tried to tell me it was a moral imperitive to get up early and get to work, to show the bosses I cared. For some reason staying late didn't show the same thing, particularly if i took advantage of the flex time and showed up around noon. Fortunately this guy was not my boss, and instead I get to be productive in the way that fits me best. Fortunately this guy broke off the mentorship after I got promoted in spite of my "terrible scheduling habits".
req2 17y ago
It's easier to observe and control for the sleep schedule and then measure alertness, rather than the other way around.

embeddedradical 17y ago

although this may be true, the study is quite superficial. personally, my issue with sleep has been that if you leave me alone in a dark room (like in my bed), i'll come up with all sorts of ideas... also, distractions taper off as the night progresses, and i'll be like 'k, this feature, then done' - but then you realize you need another feature but you have all this information in your head you need to get out -- and the details keep piling in. if you were to jot down notes, you might as well have coded it and tried it out.... and then you realize something else you can do. other nights, you go ah, this is nice, and just know what the next step is and as long as it's somewhat concrete, it's easy to sleep knowing you'll do it tomorrow. generally, i find it easier to sleep if i've hit one of these plateaus, or if i'm stuck, or if there's too many options of where to go from here; the answer will be clearer tomorrow. It's when the answer is -almost- clear, just need to try out a few things, that sleeping feels like trying to swim upstream. i've tried to 'fix' my sleep so many times in life now, by which i mean be consistent - and so far, no success. nothing too bad has happened to me, either -- if i don't get enough sleep i know i'm sub-par but i feel capable of at least being 'average' until i get home and get more sleep the next night. on the other hand, i've taken vacation simply because i know if i don't solve this ranking algorithm, i'm going to go insane - so i took three days off (wed-fri, so i got weekend too), and worked through the day and night, sleeping as fit until it was all good, and that itch in my head was resolved.

billswift 17y ago

The claims in the article, including those specifically attributed to the researchers, go far beyond anything justifiable by the research. The "genetics" claim is especially unjustified. Personally, I can and have slept and worked ANY schedule, as long as I can get enough sleep. Creative work or intense studying though work best with a split schedule, where I have two 3-5 hour sleeping shifts, so I am always fairly fresh.

pygy 17y ago
The genetic origin of the variation in circadian phenotypes are well documented, and have been for a long time. You can work against your predispositions, but if you remove social constraints, your natural pattern will quickly re-emerge. Furthermore, your subjective assessment of your productivity along the day is not really meaningful in this context.
- Goladus 17y ago
  Smug early birds take note: Night owls actually have more mental stamina than those who awaken at the crack of dawn, according to new research. "It's the late risers who have the advantage, and can outperform the early birds," said Philippe Peigneux He's not actually talking about "performance" in a general, life-applicable sort of way; rather he is talking about performance at specific mental tasks. You wouldn't think that from the way the article is written, however.

Mistone 17y ago

working my regular job and doing a side startup has def made me embrace the night-owl shift. I find that my first hour of night work, say 9-10, is less productive then I'm able to pick up the pace from 10-1, at that point I have to go to sleep or I'm wrecked the next day. Ideally, when I'm able to go 100% on the startup, I would work from 8:30-5:30, come home chill with the fam, then work 9ish-1ish. that way I get 6 hours sleep, have time to hang with kids and still put in a solid 12-13 hours. funny that my dream is to be able to work 13 hours a day, but its really about doing something I love and own, and the crazy hours are a side result.

rokhayakebe 17y ago
If you have a startup and a day job I urge you to secretly work on your startup as much as you can while at your day job. This is wrong, but gotta do what you have to do to do what you want to do.

pygy 17y ago

Here we go again... People with nothing but their own anecdotal experience about the subject trying to (and failing at) criticizing a scientific paper. No one has pulled off a "correlation != causation", but most other usual suspects are already there. Disclaimer: 1) I work in neuroscience , but not in sleep research. This (hopefully) makes me qualified to assess the seriousness of the methods, even though I don't have much background in circadian rhythms. 2) I'm biased in this case since I know personally the first author of the paper and some of the other researchers involved (and they are among the smartest and more conscientious people that I know of). If there were any methodology error lay people would be able to spot in the paper, it wouldn't have been published in any respected journal in the field (and most people who commented here are lay people regarding (sleep) science). This is Science Magazine... They have the best reviewers in the world ("best" as in "smarter than you can probably imagine"). There are shortcomings inherent to this kind of study, of course. You cannot control experimental parameters like you can in physics or chemistry. That's why you have to 1) build your research on solid ground (i.e. solid results already published and reproduced) and 2) be as careful as possible in designing your protocol in order to have your bases covered. Schmidt et al. used the gold standard, they're frankly out of reach of such "low hanging" criticism. </rant> I enjoin you to have a look at the paper and the supporting material. _ Full text: http://www.innovatieforganiseren.nl/wp-content/uploads/2009/04/516.pdf http://www.innovatieforganiseren.nl/wp-content/uploads/2009/... Supporting Online Material: http://www.sciencemag.org/cgi/data/324/5926/516/DC1/1 http://www.sciencemag.org/cgi/data/324/5926/516/DC1/1 _ Here's the beginning of the latter: _ 1. Material and methods Subjects. [Ethical committee disclaimer]. [All subjects] were screened for morningness or eveningness according to their timing preferences as defined by two questionnaires (MEQ (1) and MCTQ (2)). The two groups were matched according to age, sex and educational level and did not differ in their anxiety and depression levels as well as in sleep quality and day time sleepiness (all ps > 0.1; Table S1). Morning and evening types significantly differed in their scores on the two chronotype questionnaires (MEQ and MCTQ). Exclusion criteria were reports of medical, psychiatric and sleep disorders, medication or drug consumption, alcohol abuse, excessive caffeine consumption or physical activity, shift work within the three past months, and transmeridian travel or disturbances in the sleep-wake cycle within one month before the experiment. Design and Procedures. An overview of the study design is illustrated in Fig. 1 of the main text. Individual times were scheduled according to each volunteer’s preferred sleep and wake timing. Criteria for such timing preferences included sleep schedules adopted on free days as assessed by the MCTQ (2) and after interviewing the subject to ensure that the scheduled timing was as close as possible to the schedule that he or she would spontaneously adopt. In a second step, the screened subjects came to the sleep facility for a habituation night. After this night, they were asked to follow the sleep schedule (± 30 minutes) they would spontaneously adopt while free from any social and professional constraints. Target bedtimes and wake times were determined for a sleep duration of about 8 h (± 30 minutes). To assess the subjects’ compliance to the selected rest-activity patterns, motor activity of the non-dominant arm was recorded using actimeters the week prior to the experimental sessions along with sleep-wake logs. After this week under actimetry recording, subjects came to the sleep laboratory for 2 consecutive nights. The precise schedule of each session was individually adapted according to the subject’s habitual bedtime on the basis of the mean timing of the subject’s sleep midpoint derived from actimetric data of the preceding week. Subjects reported to the laboratory 7 hours before habitual lights off on day 1. After the hook-up of the electrodes, they continuously stayed under controlled conditions in dim light (< 10 lux) in order to avoid the influence of bright light on circadian rhythmicity parameters (3) and in the aim to equalize pre-scan conditions between subjects. Subjective sleepiness (Visual Analogue Scale (VAS) and Karolinska Sleepiness Scale (KSS (4))) and objective vigilance (a modified version of the PVT (5)) were assessed at hourly intervals while awake. Furthermore, hourly collected saliva samples were assayed for melatonin using a direct double-antibody radioimmunoassay validated by gas chromatography-mass spectroscopy with an analytical at least detectable dose of 0.65 pg/ml (6). Circadian phase was estimated by the calculation of the mid-range crossing time of salivary melatonin (7, 8). For each individual curve, the maximum value and the minimum value was averaged (mid-range value pg/ml) and taken to determine the mid-range crossing time (time of day, h) on the abscissa. Polygraphic data (see below) were recorded during the nights preceding fMRI sessions. After lights off, subjects were allowed to sleep for 8 hours. Then, 1.5 (morning session) and 10.5 (evening session) hours after wake up of scheduled sleep timing, they underwent a fMRI session during the practice of various cognitive tests, including the psychomotor vigilance task on which we focus here. For half of the subjects, the morning session followed the first experimental night and the evening session the second night, whereas for the other half of the volunteers the morning session followed the second experimental night and the evening session the first night. Subjects were allowed to leave the facility between the two experimental nights. They stayed in the laboratory under dim light conditions (<10 lux) for at least 4 hours before the scanning sessions (see dashed line in Fig. 1). They wore protective glasses avoiding excessive light input when going to the scanner room. The order of selected cognitive tasks was counterbalanced across subjects and sessions. Before the start of the experimental protocol, all subjects underwent a short habituation scan session in order to familiarize them with the noise and the body positions associated with the fMRI environment.

ivankirigin 17y ago

Intensity and focus matter more than stamina. The stamina that matters is over the course of months or years.

scotch_drinker 17y ago

Aren't we just comparing apples and oranges here? Is it really that counterintuitive that people who get up at 5 AM tend to not be terribly mentally acute at 3 PM? Is it counterintuitive that night owls would be more mentally acute later in the day? Let's see a study that measures the mental acuity of extreme morning people at 7AM and the mental acuity of extreme late risers at 2 PM. Better yet, let's measure mental acuity of the two groups immediately upon waking. Surely that must be just as significant as the study above. Studying the mental performance of two groups when one group is seriously disadvantaged (and if you think people who get up at 5 AM aren't disadvantaged at 3 PM, I think you're not being honest) isn't particularly note-worthy if you ask me.

pygy 17y ago
The measurements were performed at time points relative to the natural rhythms of the subjects i.e. respectively 1h30 and 10h30 after waking up according to their natural rhythms. Have a look the methods and protocol linked above.
- scotch_drinker 17y ago
  That's not what the article says. The article seems to draw its conclusions entirely on this statement: "After 10 hours of being awake, the early birds showed reduced activity in brain areas linked to attention span, compared with the night owls." I saw from your comments above that measurements were taken at two different times. However, the article, not the study, is linked prominently on the front page of HN and that's what I'm taking exception with. I have no doubt that the study is rigorous and careful but the conclusions drawn and the tone taken by the author of the article are sketchy at best. On top of that, as you mention in a previous comment, the study is comparing what the two groups can do in "their relative evenings". Again, this seems like apples to oranges to me. Of course morning people are going to be less effective in their evenings because, well, they are MORNING people. I guess I would be interested in understanding what we hope to get from a study like this. The article says people who are extreme in either direction are genetically predisposed to their own personal direction. If we identify that one group of people is better than the other based on their genetics, what does this do for us, long term? That's something I'd be interested in hearing about.

biohacker42 17y ago

Why does this cheeky crap article have 52 freaking points? Oh sorry I'm supposed to flag and shut up, not complain.

Goladus 17y ago
The research is interesting, despite the crappiness of the article.