Just how important is that eight-hours of rest?

This past week, I was in San Francisco for a week-long conference. San Francisco is a wonderful city, but it's a bit of a pain for me to get to, as it's pretty much the single furthest point in North America from Montreal, Canada, where I live. Much of the distance between them is North-South, but going from the coast of the Atlantic ocean to the coast of the Pacific still entails a three-hour time zone difference. For the week that I spent there, my sleep schedule was chronically disrupted, both because my body's 11pm was my clock's 8pm, and because I was waking up early for the conference and going to bed late due to... well, let's call them "non-academic activities." Midway through the conference, I attended a lecture on recent advances in sleep disorders and their medical treatment; I was far from the only person in the audience to note the irony.

In most role-playing games, sleep is pretty straightforward: you go adventuring for sixteen hours and you sleep for eight hours, repeating as necessary. If you're a spellcaster, you actually sleep less than that, on account of having to either pray or prepare spells, but the rules don't swell on that. Oh, sure, there are various spells and effects that can cause nightmares or something and thereby inflict some penalties on a character, but by and large the rules just assume that everybody gets all the sleep they need. It would seem that nobody in Toril suffers from insomnia and no one in Golarion has sleep apnea, and while nobody sleeps well in Barovia or Darkon, it doesn't have much in the way of in-game effects. Think about it, though. Adventurers spend their lives traveling to ridiculous places, fighting until they drop and then rising to do it again the next morning. Does everybody really get such a good night's sleep curled on a bedroll in a freezing dungeon, with the sounds of partying goblins echoing up the tunnel all night? Even with eight hours set aside for rest, this means that most characters in a party actually get less than that, on account of studying, equipment maintenance, and guard duty. Granted, a physically-exerting lifestyle probably means that most adventurers collapse into bed and fall asleep instantly, but it's still hard to imagine that everyone is always so well rested. And if they are that well-rested, then I'm jealous, because I know that I certainly feel like I'm carrying around an intelligence penalty most days.

Despite some very forgiving rule mechanics, sleep deprivation is actually extremely quick to affect humans, and those affects can be profound. Most insidiously, study after study has shown that most people are actually terrible at judging their degree of sleep-related cognitive impairment; sleep-deprived individuals constantly under-estimate just how badly they've been affected, which means they may do risky things without having any insight into the fact that they're performing sub-optimally. How does medicine know so much about sleep deprivation? Aside from thousands of animal studies, medicine has drawn upon a number of populations who are chronically sleep-deprived, including truck-drivers, university students, and of course, ourselves.

Just for fun, I took a quick look through the literature to see what it has to say about sleep-deprivation. Then, when I found about ten thousand papers on the topic, I restricted myself to studies on humans. Then I restricted myself to only papers published in the past year. When I still had some twenty relevant papers on the subject, I decided to just glance through a bunch of them pseudo-randomly to see what people are saying. I'm only presenting studies here that looked primarily at behaviour, as opposed to studies that directly measured growth or shrinking of synapses in the brain following sleep deprivation. The point is, a LOT of work is being done on this subject, and a lot of it suggests lack of sleep is a bad thing.

Hogenkamp et al, Psychoneuroendocrinology, S0306-4530(13)00017-6. Acute sleep loss increases food intake, as well as poor decision making in terms of food choices. Men subjected to a night of total sleep deprivation ate larger portions of food and felt hungrier than controls who had slept the whole night. They snacked more during the subsequent day, too.

Ramdani  et al, Biol Psychol, 93:237-45. Individuals forced to stay awake for 26 hours had significantly greater difficulties controling their impulsivity and made more errors on a reaction task. They were less able to notice their own errors.

Pizza et al, G Ital Med Lav Ergon, 34:375-7. Sleep deprivation and obstructive sleep apnea both led to a similar increase in car accidents in a 30-minute, monotonous driving simulator.

Tobaldini et al, Eur J Intern Med, in press. Immediately after a single night on-call, internal medicine resident physicians showed signs of poorer immune function and cardiovascular regulation.

Wali et al, Ann Thorac Med, 8:22-7. A single night on call impaired mood and cognitive performance of junior doctors.

Emmett et al, J Paediatr Child Health, 49:246-50. The families and spouses of pediatricians reported that the day after a night shift, the family relationship was worse and it was harder to enjoy quality time together.

Fraser et al, Ergonomics, 56:235-45. Sleep-deprived participants were less able to win at blackjack, had poorer judgment while playing, and had difficulty making use of external support to help them make decisions.

Skein et al, Int J Sports Physiol Perform, in press. Rugby players who failed to sleep after a game recovered more slowly, both mentally and from physical injuries.

Zagaar et al, Sleep, 36:751-61. Regular exercise appeared to reduce the impact of sleep deprivation on performance.

Unfortunately, all of this is stuff that would be painfully difficult to conceptualize in game mechanics. Intelligence and wisdom penalties would cover much of it, but not in a sensible form. On the other hand, some data certainly seems to suggest that a more active life style reduces the impact of sleep deprivation, and you would have to imagine that this is one advantage that adventurers have.