Experience drain

Field experience is converted to ranks every 200 seconds, with each skill having a separate 200 second timer. The amount drained is dependent upon a number of factors, position in the wall rank cycle, the character's Wisdom, and to a lesser extent, the character's Discipline. While not directly helpful, the character's Intelligence does play a part, as the amount converted to ranks is a percentage, and Intelligence will increase the size of the experience pool. Likewise, having more field experience will also increase the pulse size, due to the percentage nature.

Experience Drain at Login

Experience drain at login is a process that is applied about 10 seconds after a character logs in. Depending upon how long it has been since the character was last in game, a portion of field experience will be converted directly to skill ranks.

As per GM Ssra, the times are roughly as follows:
< 30 Minutes - 0%
30 Minutes - 6.25%
2 Hours - 25%
4 Hours - 50%
8 Hours - 100%

Experience drain at login only occurs for players who have not receieved a warning within the last 6 months.