Thursday, May 22, 2014

Water, food and sleep

Usually we assume our characters rest and eat appropriately, and do so even deep in a dungeon, threatened by monsters that dwell in the deep passages and tunnels. They eat "iron rations" and take turns to sleep. But what is the true effect of not sleeping or lacking abundant food and water? What happens when these effects accumulate over time or become compounded as food lacks first, then water then sleep? To show this effect I've drawn up some graphs that show the combat effectiveness of men as these three things become scarce. I've also added some rules to manage this in a game.
The graph below shows the effect of no sleep, no water and no food over the course of days. Notice the steep slope for sleep and water compared to food. Now I don't believe anyone can go for three of four days without water or sleep without serious impact on their bodies. So dropping to an effectiveness of less than 40% can be very limiting indeed. A state of extreme weakness, disorientation and near comma. In game terms going below 60% should be very limiting and reaching 50% should be very impacting indeed. Very strong penalties at that point.

Spending a day without food drops effectiveness by 12%. This can be represented in game as a light penalty when performing actions. On the other hand, a day without foot or water drops performance by an outstanding 25%! And a day without water and sleep drops performance by a whooping 45%! By the end of the second day the character's performance drop due to lack of water and sleep would drop by 70%!!! A near death situation if you ask me.

Lets now consider situations in which sleep, food and water are not totally lacking yet they're not available in sufficient quantities either. We can imagine that such shortage would accumulate over time. In this case characters having a fraction of what is required will eventually build up a whole day's worth of loss, specially when doing strenuous activities such as exploration, travelling and combat. For example going with half the required amount of water will build up the equivalent of a day's lack of water over the course of four days.

Consider the following rules:


  • A day without a warm meal counts as 1/8 of a day without food.
  • A day with half a ration counts as 1/4 day without food.
  • A day with one fourth of a ration counts as 1/2 day without food.
For example, travelling over tundra without a fire to cook will accumulate 1/8 of a day for each day. After 10 days of travel the character is suffering from a day's worth of famine (10/8 days = 1.2 days). Spending four days eating less than 1000kCal (half ration) is the equivalent of a day without food. If the rations are eaten cold it's the equivalent of a day and a half without food.

  • A day with less than 8 hours, but more than 6 counts as 1/8 day without sleep.
  • A day with less than 6 hours, but more than 4 counts as 1/4 day without sleep.
  • A day with less than 4 hours, but more than 2 counts as 1/2 day without sleep.
Your party has been pursued non stop for the past 48 hours and has only managed to sleep about 3 hours every day. This is equivalent to a whole day without sleep and effectiveness drops by 25%.

  • Each day with less than 2 liters of water but more than 1 liter counts as 1/8 day without water.
  • Each day with less than 1 liters of water but more than 1/2 liter counts as 1/4 day without water.
  • Each day with less than 1/2 liter of water but more than 1/4 counts as 1/2 day without water.
These quantities need to be adjusted for climate. Being twice as much in hot climates and four times as much in desert climates. The later can be reduced to three times if the character's activities are restricted to the cooler hours of the day.


Modern War in Minature, Michael F. Korns

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