I have seen way to many places where a method takes a long or an int to represent durations in either nanoseconds, milliseconds (most common), seconds and even days. This is a good place to look for errors, too.
The problem is also quite complex once you realize that you can mean for the duration to be a certain number of seconds, or an interval that fits the human perception of time better, so that a duration of 24 hours is always going to be the next day at the same "wall-clock" time. Or that a year is either 365 or 366 days depending on the date, so that a year from 28th of February is always going to be the 28th of February.
Why is there no distinct type to represent this? I have found none in either Java or .net