This week I read the fascinating book Dreamland : adventures in the strange science of sleep by David K. Randall. It’s a journalistic book on the current state of ‘sleep science,’ focusing on interesting anecdotes about the history of the study of sleep and dreams. It’s all very interesting, since we all sleep, and there is quite a bit of useful and surprising information about sleep and our circadian rhythm. I found three things that might be useful for RPGs:
1) Randall mentioned the work of A. Roger Ekirich, who has written a social history of the night (yeah, I’ll read that soon). His description of how people in the medieval period feared the night is pretty important if you do any campaigning in civilized areas. Everything shuts down after dark, and apparently the night-time streets of any large town or city would be very dangerous, as frightened people stabbed first and asked questions later (is that a robber? or worse? en garde!). City or town gates locked at nightfall and if you hadn’t gotten inside, you’ll be spending the night with robbers, animals, werewolves, witches, etc. Not really a big surprise but a good reminder to make your medieval peasants/townsfolk/etc. terrified of being caught outside at night, hirelings included.
2) Ekirich and and a scientist whose name I forget just now independently discovered another fascinating thing: before the industrial age and widespread artificial light, humans normally had two ‘sleeps’ each night. The first sleep ran from dark to midnight or so, and and the second began sometime an hour or so later. In between, people pretty much universally woke up and spent an hour or more praying, reading by candlelight, or having sex. Waking up in the middle of the night is seen as a sleep disorder nowadays… Anyway that probably makes things a little easier when the party is camping out and changing ‘watches,’ and adds a short ‘intermission’ for those indoors when adventure hooks might happen (“you hear footsteps/yelling/etc. in the middle of the night”).
3) Lastly, scientists have been measuring how lack of sleep impairs cognitive ability, and as a rule of thumb we lose 1/4 of our cognitive ability (reasoning, memory, etc.) for each 24 hours gone without sleep. So there’s a benchmark for penalizing the PC that stays up all night keeping watch, traveling, memorizing spells, or whatever — multiply mental stats by .75 for one night’s sleep lost, .5 for two, etc. Physical abilities are impaired as well, but I didn’t find a quantitative measure of that, so you’re on your own there.
Anyway I would recommend Dreamland as a very interesting book on its own merits and as a useful bit of information for DMing.