6 hours of sleep showed cognitive performance that as bad as not sleeping for 2 days straight

“After 10 days, subjects restricted to 6 hours of sleep showed cognitive performance that as bad as not sleeping for 2 days straight. However, they didn’t report feeling sleepy even as their cognitive performance declined.” https://ncbi.nlm.nih.gov/pubmed/12683469


All the people that still swear by 6/6 and all the companies that condone it should read this.


Here’s the paper: https://watermark.silverchair.com/sleep-26-2-117.pdf?token=AQECAHi208BE49Ooan9kkhW_Ercy7Dm3ZL_9Cf3qfKAc485ysgAAAmYwggJiBgkqhkiG9w0BBwagggJTMIICTwIBADCCAkgGCSqGSIb3DQEHATAeBglghkgBZQMEAS4wEQQMgBh75ZWcnUMU5GR0AgEQgIICGXHpaZKwGw09TAIHfqAojSYcGzT119XQhP4AEZGRYvMMDoyv6vhbKQiGpdnDeohU3XrD68Z9RyPA8Rfq46TTFuioC6CqVs8kHHnuS4UZ-4cKOtUBInFngNQ6SmhNZvQZU2ejeJbnzrf6iHVQn_NalO-8mFMhvexjCVskZJbS_2zk2z2NmGdpCl_d86W2Y4UIsBP9wV3DrGvb8Zl3QnZHp3q6pzHV4wwRfWgp-XHLFL4Fpp-WRybaEZ-dMBHymawPrSKwEXSvoevshZPshbahgxR--H5ueuF2Pgm36wLzLb1glY1OmpO2Vo74iMVWZ9-FTs-yBwUrcrzySrkw-F3a9URSnyw1syGCdJlpQV6axIwH7PDiG1jtteHD0w6_AI8GouShUULPMf9roEjTojPHLSFKaiYA01WWwybJ_cupy6wlb1KDRVuifdfQWsGR9V44_NJhovRoXyTY1KjoCnUlC1tMVmgiP7MStbh83_3rN60aicEPxAqrKyTx01H_LArTgGC1O4TdfhawkkUsHW2yXGxJFdOTFTwXrmd6QDfW7Tq300TMlICNANoGLhJUq4SfcJOoIuOomjvSg7lLzdCwhEszhS3MEbQXiaKDnYniI9N0atmiRYH27NLrYzNV9dYgJKYHT8DkicjeFkVBrk_7jUCJKNw5K7Er04-cdoFlChl9OdC2IGA5zGiYvF_2rlTLDgaFt40UuvZmsQ

That’s quite the link but you need all of it.

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I don’t disagree with you – but in fairness, the paper talks about increasing deficits with total awake time greater than 15.84 hours per day, not necessarily one continuous sleep period.

There’s probably another paper waiting to be written about that. :wink:


On principle I never use obfuscated links and am extremely reluctant to click on them. I want to know exactly where I’m going before I go there.

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Yeah, add it to the thousands already written - and promptly ignored by regulators - since WW2.


Nodded off trying to read it.


No need to read it, just read this:

“After 10 days, subjects restricted to 6 hours of sleep showed cognitive performance that as bad as not sleeping for 2 days straight. However, they didn’t report feeling sleepy even as their cognitive performance declined.”

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If you are doing 6/6 who gets 6 hours in one stretch? I know back when I was doing it back in the day I was lucky if I got 5 on the rack.


The paper says the sleep was restricted to 4-6 hrs. Be like 6 x 6 but without the siesta.

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18/6 cannot be fairly compared to 6/6 as essentially the same thing. there is a world of difference.


I use to do 16/8, 18/6, and even 20/4 on fishing boats. I certainly couldn’t do it now.

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On land, I’m fine with 6 hours of sleep a night. My Fitbit monitors it & tells me about 6 is my average. When the misses calls it day I go to sleep until I can’t sleep anymore & then I’m awake. But I never slept 6 hours straight when I worked 6 & 6 on tugs/ATB’s. It was impossible unless I wanted to go off watch early or come on late. I guess I went years with only 4.5 hours straight sleep with only a nap on the next watch. I’m bet those tug/ATB guys that I worked with are still doing the 6 & 6. It would have been easier to convert them to another religion or get them to join the opposite political party than get them to work something else. Most people don’t like change if it is what they initially learned & if it is still working. IMO, the people who can’t work the 6&6 are the ones who started in the industry working something else.

Better working link for the paper:

PDF Article Link

Electronic page 7/10 or page 123 of the article:

Accordingly, daily
sleep need to prevent cumulative
neurobehavioral deficits in these
subjects would appear to be 24 h –
ξ = 8.16 ± 0.73 h (estimate ± s.e.).

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My relief and I would sometimes relieve each other early on one watch and a little late on the other. A 7/5 technically. Made a world of difference knowing you had 5 seconds to unwind before having to be up for the next one.

the USA way 6 and 6 is one of the reasons usa cant sign up to MLC I thought?

The study I want to see re:working 6/6 is the only one that counts: for vessels operating in the same navigational environment, does working 6/6 result in more groundings/collisions than working 4/8?

It would be a difficult study to make, because the vessels that are most in peril of groundings–those vessels that operate closest to land-- mostly work a 6/6 schedule in the USA, as opposed to 4/8. The statistical samples needed for comparison might not be there.

4/8 is the norm for vessels which spend most of their underway time away from land. An entirely different navigational environment.

I did a study of navigational incidents involving Aleutian freighters, from 1980 to present. 10% were caused by fatigue, and these occurred in a narrow band of time / geography /operations, i.e. mid-1980s/ Akutan AK/ grueling king crab operations. An extreme situation not likely to be found again. 90% of all incidents in the 30 years of the study were caused by something else.

The study confirmed an interesting phenomenon I had noticed in my career. In the days of paper charts, captains/mates who had grounded most commonly used the excuse, “I was looking at the [paper] chart”.Chart tables typically face aft. Hence, as you are nobly navigating your vessel, you must turn your back to the windows. Never mind it would have taken 15 solid minutes of “looking at the chart” to run aground in a narrow channel. The excuse was just ass-coverage for these officers’ reputations, and they stuck by it in the face of all logic.

When electronic charts become the norm, the excuse changed. Plotters/integrated displays are usually mounted so the navigator faces forward. they didn’t have the excuse of having to turn their back to the situation in hand. This is when I started to hear in the media reports of such accidents the excuse “fatigue”. Most cases of groundings and collision suddenly became a result of “fatigue”.

Look at recent fatal accidents involving train operators in the USA. At a certain point, two things become common 1) the person in charge claims fatigue, 2) that same person claims they can’t remember what happened right before the accident.

My view: data from 2000 in terms of collision/grounding may be be tainted, because the officers involved will be, without fail, advised by their lawyers to 1) claim fatigue 2) claim they can remember nothing about the incident. True or not, it’s the perfect way to absolve yourself of all blame.

By the way, in the trade I work in, second mates are not required. In other words 6/6 is OK. However, most voyages sail with second mates, and they work 4/8 much of the time.


I worked 12/12 on the semi I worked on luckily the charterer had standards so there was 2 of us with 6 hour splits in the shift so fresh person every 6.
Pretty obvious after about 10 hrs you are not functioning very well…even though you have had a good sleep

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Work or stand watch? There’s no off-watch work?