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According to Daylight Savings Time and Traffic Accidents N Engl J Med 1996; 334:924-925

Major disasters, including the nuclear accident at Chernobyl, the Exxon Valdez oil spill, and the destruction of the space shuttle Challenger, have been linked to insufficient sleep, disrupted circadian rhythms, or both on the part of involved supervisors and staff.

Is this really true?

DavePhD
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  • Did you want to know if there is *truly* a link between the two, or merely if someone somewhere may have (rightly or wrongly) made such a link? – T.E.D. Nov 15 '16 at 15:27
  • @T.E.D. I want to know the truth. If you have more info to add, then add an answer. – DavePhD Nov 15 '16 at 15:44
  • @DavePhD The truth *about what*? Whether Chernobyl was caused by a humand error done because the guy did sleep enough that night? Truth about whether insufficient sleep disrupts circadian rhythms? – Bakuriu Nov 15 '16 at 16:22
  • @Bakuriu Just the Challenger. I'm limiting the question to just that accident. – DavePhD Nov 15 '16 at 16:27
  • Whilst lack of sleep may have played a role I suspect it would have been a minor one at most. Given the pressure applied by NASA to Thiokol to get them to withdraw their recommendation to not launch combined with their attempts to justify what was an obviously ridiculous decision to launch after the fact suggests that the whole management style at NASA had primed the pumps for that accident to happen. Given that the same managerial issues seem to have been a big factor in the loss of Columbia as well I suspect management culture was the prime candidate for Challenger's loss – GordonM Mar 23 '18 at 11:27

1 Answers1

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On the headline question

Has “the destruction of the space shuttle Challenger… been linked to insufficient sleep”

There probably was a link, as it was important enough included in the Rogers report. As was reported by NASA:

The Rogers Commission Human Factors Findings stated, "The willingness of NASA employees in general to work excessive hours, while admirable, raises serious questions when it jeopardizes job performance, particularly when critical management decisions are at stake."
source: NASA: To sleep or not to sleep

The cause of the accident itself is well known and was, put simply, a failure in the joint between the two lower segments of the right Solid Rocket Motor.

The relevant part of the Rogers Report for this question is human factor analysis which states:

Other studies have demonstrated that night work and shift changes produce sleep loss and fatigue by disrupting workers' Circadian rhythms.

For which that line cites:

Akerstedt, T., "Adjustment of Physiological Circadian Rhythms and the Sleep-Wake Cycle to Shiftwork." In S. Folkard and T.H. Monk (Eds.), Hours of Work, New York: Wiley, 1985, pages 185-197.

The report goes on

One group of such workers are the Morton Thiokol employees who typically work 12-hour shifts, either 3:00 p.m. to 3:00 a.m. or 3:00 a.m. to 3:00 p.m., from two to seven days (mean = 4.5 days) in a row while performing the stacking of the Solid Rocket Boosters. Both these extended work schedules disrupt normal sleep patterns by starting or ending at about the usual midpoint of night sleep, thereby producing substantial sleep loss. The occurrence of lengthened workdays of 12 to 16 hours in the preceding four case histories would also disrupt sleep by interrupting the worker's adjustment to his current shift schedule.

Jamiec
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    I may not be reading this correctly, but is there any **link** established in the report? (which to me seems to imply causation, not merely the fact that there was sleep issues) – user5341 Nov 14 '16 at 17:22
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    @user5341 it's an interesting point. I read many accident reports - usually to do with aviation, but they are not dissimilar to this report. When it comes to human factors, there is rarely one pinpointable "cause", and more often than not a chain reaction of events which led to an accident/incident. In this case I would say that the sleep habits of the NASA staff, especially those responsible for the SRB's, *could* have contributed to the accident. It was not, by any means the "cause" of the accident though. The question asked if there was "a link" and the answer is, "yes, probably". – Jamiec Nov 14 '16 at 17:28
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    If you skip to the bottom of the report, you'll see that failure of the joint was not a root cause. The joint failed because the temperature on the morning of the launch was too low: 36 F. 61 F was considered the minimum temperature by the engineering team to avoid damage to the O-rings. As I understand it, the engineers desperately tried to get the launch postponed but the presentation was so obtuse, no one could figure out what they were saying. Perhaps sleep was a factor in both the presentation and how it was no understood. – JimmyJames Nov 14 '16 at 17:31
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    Here's the [infamous data visualization](http://deepsense.io/wp-content/uploads/2015/06/image1.png). Here's an article about one of the engineers that tried to get the launch postponed: [Thirty years ago, Bob Ebeling drove ... to watch the launch of the space shuttle Challenger. On the way, he leaned over to his daughter Leslie and said: “The Challenger is going to blow up. Everyone’s going to die.”](http://www.nytimes.com/2016/03/26/science/robert-ebeling-challenger-engineer-who-warned-of-disaster-dies-at-89.html?_r=0) – JimmyJames Nov 14 '16 at 17:50
  • @user5341, if there is a link, I don't think you could expect any more "evidence" that there already is. The question is just too unanswerable. – Paul Draper Nov 14 '16 at 17:54
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    @PaulDraper - I'm afraid you are right. It's a great answer, by the way - I would add the explicit note that there's no actual proof/causation just for clarity, but it's definitely a solid well researched answer. – user5341 Nov 14 '16 at 17:56
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    @user5341 The problem with the answer is that if you say the cause was a mechanical failure, there's no way to link that to a lack of sleep. O-rings don't sleep so it would suggest that there is no link. If you consider that really the failure was caused by bad decisions and poor communication, it's a lot easier to understand how sleep could play a role in that. – JimmyJames Nov 14 '16 at 18:03
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    The *point of failure* is very different from the *cause* of an event. If that were the case, every autopsy, including those of these astronauts, would conclude that death occured due to lack of oxygenated blood to the brain. It doesn't really adequately explain the circumstances that gave rise to the situation in the first place. If you're going to backtrack the chain of events, it seem disingenuous to stop at the O-rings. – J... Nov 14 '16 at 19:01
  • @JimmyJames You can link any mechanical problem in a designed system to lack of sleep. Humans specified the requirements. Humans designed the system. Humans built the system. Humans accepted that the system met the requirements. Now, if the cause of the failure was a meteor strike, it would be a bit harder. – David Schwartz Nov 14 '16 at 20:01
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    @DavidSchwartz While this is true at a highly-abstract level, I really don't think it applies here. The assessment of the problem was not that the design of the O-rings was faulty because they designers weren't getting enough sleep years before the disaster when they designed them. The O-rings were shown to be reliable under normal operating conditions over dozens of launches. 'staff not getting enough sleep' therefore 'O-rings fail' doesn't really explain anything. It really glosses over what happened. – JimmyJames Nov 14 '16 at 20:37
  • I find this a fascinating discussion - but /modhat it's straying towards "take it to chat". If you would like to continue the conversation .... get a chat room (which I'll be interested in joining!) or flag this answer and the whole conversation can be moved to chat in an instant. – Jamiec Nov 14 '16 at 21:55
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    Lack of sleep may have been a factor in the failure of that particular mission, but at the same time, it could also be considered a factor in the success of many other missions. In other words, it's meaningless as a cause. – Mohair Nov 14 '16 at 22:07
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    Good answer, many comments are missing the central argument: it shows clear positive evidence that lack of sleep and the accident *have been linked*. It does not need to convince that lack of sleep was *correctly* linked to the disaster, or that it was the *root cause*. While it is interesting to discuss how valid was that determination, it is irrelevant to answer the question - I hope we can all agree the determination was made at the time. – Sklivvz Nov 15 '16 at 00:06
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    My problem with this argument is that it was the *engineers* working long hours, not the managers, and the issue with the explosion was a **management issue**. Feynman [goes over this](https://en.wikipedia.org/wiki/Richard_Feynman#Challenger_disaster) in detail in his second autobiography. – T.E.D. Nov 15 '16 at 15:19
  • @Sklivvz - I think the word "correctly" is implicit in the question though. Of what use is a validation of the existence of an **incorrect** link to anybody? If that's all he wanted to know, the quote in the question answered the question. – T.E.D. Nov 15 '16 at 15:25
  • I don't think merely being mentioned in the report really ought to count as "linking" fatigue to the accident. Once you're at the point of running a formal accident investigation, you're obliged to report on any dubious practices you happen to uncover that -- even if you _don't_ think they contributed to the accident on hand -- _could_ contribute to a different accident tomorrow if not fixed. – hmakholm left over Monica Nov 15 '16 at 20:38