Sleep is cheaper than many mistakes made without it.

The cost of a night’s sleep is one night. The cost of decisions made without it can run for years, and they rarely announce themselves as fatigue-driven at the time; they feel like clear thinking under pressure. That is the whole problem with the exchange.

When you are tempted to take hours from sleep to finish something, price it against the chance of a significant error. Very little work is worth more than a functioning mind the next day.