mckpickle......
Semi-kidding on the anal probe.......During some of the long-haul carrier studies, the pilots were hooked up to the anal probes for temperature monitoring over the course of the flights. The goal was to see what the body was doing at the odd hours of the night while the pilots were flying. This was in addition to brain waves monitors and pulse recorders if my memory is correct.
While it has been a couple of years since I went to that course, I do remember a few things.....
1) Most of the countermeasures for fatigue that I remember were scheduling based and therefore not subject to pilot control. Of course, many of these strategies are simply ignored due to the fact that it might take some time, effort and money to implement scheduling consistencies.......i.e. working an early morning flight followed by a late night one the next night is not so good.
2) NASA advised regulated naps in the cockpit of not more than about 45 minutes......Much longer than that and you go into a deeper cycle of sleep that is more difficult to pull out of......45 minutes is enough to get some renewed energy without feeling groggy afterwards. I'm not aware of any carriers that have approved this policy formally.
3) No matter what you do, when your body has had enough it WILL sleep....the scariest part of the whole course was the discovery by NASA that some very fatigued pilots in their studies were UNINTENTIONALLY taking micro naps on final approach. These microsleeps only last a few seconds but these pilots were asleep on final.
NASA was able to determine the exact second someone nods off. There is no "falling asleep" in the sense that it is a gradual process. By measuring brain waves, they determined that you are either awake or asleep....there is no inbetween though there ARE various stages of sleep. They could plot the exact second the pilot(s) were awake then asleep.
In some of the long haul studies, they specifically asked some pilots to stay awake.....Now, with the NASA observers in the cockpit and with these guys hooked up to various sensors and probes, despite being told NOT to go to sleep, what NASA found was that once the body hits the wall, it doesn't matter......you're going to sleep whether you want to or realize it or not.
Interesting stuff........
Just don't be like the various crews over time that have been reported to have BOTH fallen asleep......Reminds me of one a 747-400 pilot told me.......On a 14+1/2 flight he had gone back to the crew bunk to sleep while the relief crew flew after he had flown the first few hours. After about 5 hours he got up to use the head and decided to peak in on the cockpit. Both the ca and fo were fast asleep and snoring up a storm. The senior ca stood there a while hoping to see someone at least roll their head and take a glance at the panel. After 10 or 15 minutes or so, the relief crew was still out..........The senior ca noticed those big ol' fire warning test buttons, reached out and hit all four at once. Apparently it was lucky that the relief crew were belted in 'cause they would have ejected themselves out the top of the airplane otherwise......
After chewing their butts, the senior ca had them go back and look at the face of every pax on the airplane and then go back to the cockpit and explain to him why, for their major airline 747-400 salaries, they couldn't stay awake for their shift.
Wonder if those guys ever fell asleep after that?????
We do often lay back and study the light patterns of the overhead during various degrees of eyelid closure. 
