So, basically when does sleep deprivation start to slightly affect a daily task? For example, how long would it be before it became “not recommended” to drive? What about “illegal” to drive/operate machinery? I actually did google this and found absolutely nothing.
I’m more interested in a timescale that gives a (general/approximation) of when sleep deprivation begins to seriously affect judgement and general ability. All I’ve found on the internet is articles on long-term health effects and symptoms.
Here are the Basic Fatigue Management rules set by the Australian National Heavy Vehicle Regulator for various periods.
You may also be interested in this blog post by Mark Manson today How to be More Productive by Working Less which contains an interesting anecdote about working long hours.
I caused a serious accident by falling asleep at the wheel when I was very healthy and 29 years old. I was sleeping 6 hours a night, and trying to catch up the weekend. I did this for a week, one weekend, and three days, but honestly, it was luck of the draw that it happened the day it did. Cumulative effect probably played a role, in that it was unlikely to have happened on the first day, or even the second, but it could well have happened on the fourth day of the first week, or the first day of the second week. I was drifting off for a few seconds from time to time almost every day, and No-Doz and coffee didn’t make much of a dent in it.
FWIW, I learned my lesson. I would be late to my own coronation if I was sleepy behind the wheel. I pull over and catch a nap in a truck stop parking lot or just wherever I can if I ever get the least sleepy behind the wheel, but mostly, I don’t get in that situation in the first place. If I don’t sleep well the night before I’m suppose to drive some place on the highway, I call and say I’ll be late, and try to catch a few more ZZZs. I also don’t let anyone back me into a schedule where I can’t sleep properly.
As far as how long you can go without sleep, it depends on a lot of things-- how soporific is the task (driving is very), and are you getting regular meals. Sometimes truckers live on Slim Jims and coffee. That probably contributes to fatigue.
Soldiers work long shifts, and miss sleep, but the (US) military does make sure soldiers get fed. Doctors and nurses work long shifts, but because they often work in groups (or in the case of doctors, have chances for naps), they can talk, and stimulate one another into remaining a little more alert. They also get meal breaks.
there are too many variables for an exact answer. different people have different tolerances for lack of sleep. nutrition and fitness are also large factors. legally you could drive as long as your motor skills and reaction times are good enough to keep you aware and in control. same goes for working a precision / skill oriented job. one person might begin to make mistakes at 24 hours, another at 32, another at 48, 72, etc.
one thing I know for sure is that nutrients are always better than drugs at fighting sleep deprivation. a healthy, easy to digest meal (fruits especially) will always give you more energy and focus than a coffee or a red bull. that’s just a fact. im not saying coffee isnt great im just saying the better you eat the longer you will last in any challenging situation.
I once stayed up 24 hours working on a rush project. It was not fun. On the other hand, interns used to have 24 hour shifts, but they could take a nap if not actually working. And a friend of mine had a horrendous operation in which they worked for 24 hours, then took an 8 hour break, and then came back for another 10 hours.
I once studied for 72 hours straight during my senior year of college during finals. I aced all of my exams but I wasn’t safe to drive (as I found out the hard way - no accidents but close).
Shortly thereafter, I tried to drive from Louisiana to New Hampshire in two days by myself and literally could not do it physically. After 16 hours my second day of driving, I started hallucinating and seeing people and animals running in front of me. Then it started raining and I was lucky that I found a motel at all less than 100 miles from my final destination. Not safe.
Everyone has their personal limits but I work in an industrial facility with a lot of ambitious people that get generous overtime. Some of them try to push their schedule to the max because they can potentially make a lot of money in their terms. 12 hours a day is the max for anyone and 10 hours is the max for heavy equipment operators. Everyone has to take at least one day a week off with no exceptions. Airlines have similar restrictions and that is the reason why flights can get delayed or cancelled if the flight crew has exceeded their time.
I hear people claim all the time that they work 60, 80 or even 100 hours a week all the time and that cannot possibly be true. Either their definition of “work” is very generous or they are superhuman. You can’t sustain focus and endurance for that long for any reasonable definition of work unless you are just referring to a blended work-life lifestyle.
I have worked 70 hours a week several times and refuse to do it again. Do the math. That means something like 8am - 9pm Monday - Friday plus 8am - 7pm on a Saturday or any variation of that. Sure, it is possible in short stretches but nobody can sustain that type of schedule if they are truly working and focusing the whole time.
I used to have a salaried job that was extremely cushy for 48 weeks a year. I worked for a company that produced corporate events. The events included most of the fashion shows held in NYC during “fashion week*”.
So, for 48 weeks a year the schedule was light, we’d usually start and 10 and finish at 4 with long leisurely lunches. Then we’d approach fashion week - I’d bring a suitcase into work knowing I wouldn’t see home for the next week. My employer had showers and lockers installed for these times. I easily worked over 100 hours during these weeks.
I did not drive at this job. I saw the hazards in being a licensed driver so I lied for years and told these people I didn’t know how to drive ( in NYC this is very believable).
But one of my colleagues that did drive while sleep deprived described falling into microsleep at red lights and dreaming that they were green.
Fashion Week as changed over the years, now it is centralized and organized. But back in the day each designer hired their own venue and production company. It was crazy.
The research behind current US duty regulations for pilots indicates that a person who’s been awake 16 hours is as impaired as someone freshly awake from a good night’s sleep but with a BAC of 0.04. In other words, almost dangerously impaired.
Not that’s *not *after 16 hours of work. That’s after 16 hours of simply being *awake *even if the whole time was idle relaxation.
Our normal workdays are about 10 hours at work = 12 hours since wakeup and we can really feel the difference by then. We’re also paying real close attention to how we’re feeling & acting.
One of the hazards is that as you get more tired your subconscious adopts an “I don’t care anymore; I’m just sleepy”. That “I don’t care” part is how people fly, drive, or machinery-operate themselves into a deadly situation. So the smart worker doing risky stuff is on the alert for the “I dont’ care” attitude setting in and quits working promptly. Soon enough you’ll learn when that happens to you.
For non-risky tasks like studying / cramming, beating a deadline at an office job, etc., I’m a real believer in the massively diminishing returns for any work past about 10 hours of work or 14 hours of awake. You (me really) become a zombie moving and thinking in slow motion, unaware that time is flying by while very little useful is getting done. Once that sets in it’s far more efficient to sleep now and work later when fresh.
Long before sleep deprivation sets in, precision tasks suffer as fatigue builds up.
I no longer work as late into the evening as I used to doing surgical pathology work. It begins to take longer to accomplish a task, as I’m aware I’m tired and not as efficient/proficient.
A tip for those contemplating elective surgery - try to avoid being one of the surgeon’s last cases of the day. They probably think they’re A-OK and maybe they are, but I’d just as soon not be (for example) their fourth robotic prostatectomy case in a ten-hour period.
I once worked over 30 hours straight on a real rush computer system. Then went home & crashed.
When I came back in the next week to continue working on that system, I found that my errors increased significantly after about 18-20 hours. The last 4-5 hours had so many errors that it was almost useless work.
Following on from this. Our company has a “fatigue likeliness” tool aimed at pilots that takes three pieces of information and calculates the likelihood that you would not be fit to work.
The required inputs are the hours you’ve slept in the previous 24 hours, the hours you’ve slept in the previous 48 hours, and the hours you will have been awake for when you’ve finished your current duty.
If you’ve had adequate sleep in the last 24 and 48 hours then the calculation is based purely on hours awake since your last sleep, which is the case the OP is asking about.
The tool assigns points with more points meaning a higher likelihood of getting fatigued. Anything up to 18 hours awake and you get no points. Every hour after 18 you get 2 points. With 1 - 5 points it is recommended that you self monitor, with 6 - 10 points you should notify other crew members and apply countermeasures (such as reassigning tasks, having a nap if possible, etc), and with anything over 10 you should consider not operating in general and you should not operate a “back of the clock” duty.
This says then that 18 hours is fine, 18 - 23 is of some concern, and 24 hours is definitely a problem. It should be emphasised that this assumes you have had adequate sleep. If your sleep in the last 24 hours wasn’t great then the fatigue score gets significant penalties. It should also be noted that the tool is a guide and should not be used to “make your decision for you”, it particularly shouldn’t be used to justify a go decision when your body is telling you the opposite.
This gives more forgiving results than the 16 hours awake = BAC of 0.04 equation would suggest but I don’t think they are significantly at odds with each other.
Fun fact: in the US, there are no legal work-hour restrictions on aircraft mechanics. None.
FAA-certificated aircraft mechanics are required to have 24 consecutive hours off in any consecutive 7-day period, or the equivalent. Which means that the mechanic working on your airliner might be on consecutive work day 28 (with work hours not restricted by law), before he/she gets 4 days to catch up on sleep, family, and life before he/she starts another 28-day grind.
Personally (anecdote =/= data…), I can work 2 consecutive days with no sleep - BTDT. But by the end of the second day, I am not safe in just about any capacity.
This is what I’ve called the point of “negative productivity”, after which you’re more likely to introduce errors that work against successful completion of the task and will force rework to correct. For me, that was also at about the 20-hour mark, but working in a team helps cover for some of that (we don’t all necessarily make the same errors, and can catch each others’ before they get too far), so in a team of sleep-deprived brain-workers I will say that negative productivity sets in a few hours later. 24-26 hours, effectively, at which point team-based checks and balances will fail as exhaustion overrides group strategies and behaviors.
My daughter-in-law analyses cytology samples. To maintain accuracy, lab workers are restricted to a regulated maximum number of samples per day. If a worker is fast, they can go home early.
There are also quality control checks to be sure that workers are taking enough time to be accurate.
My sister just started a nursing job in Texas working 16 hour shifts (this is not 12 hr shifts + occasional overtime, she’s scheduled for 16 hours.) I’m amazed this is legal. Who thinks this is a good idea? Do we not want our medical staff to be mostly awake?