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Here is an interesting account of sleeping on the alterter and reflexive resetting:   7. The 2004 Macdona Accident, and Automatic Behavior Syndrome Additional insight on “alerter naps”, microsleep episodes, and the limitations of conventional activity-based alerters can be found in the 2006 NTSB investigation report of a collision between two freight trains in Macdona Texas at 5:03AM on June 28, 2004 [25]. The engineer and conductor of an activity-based alerter equipped32 freight locomotive had both accumulated significant sleep debt33. The engineer had been driving slowly west bound, fighting sleep for at least 45 minutes prior to the accident, and the conductor was probably fully asleep. Evidence suggests the engineer had a microsleep episode, but roused himself and made a precautionary speed reduction using dynamic brakes and slowed the train to 22 mph. However, thereafter he apparently drifted in and out of micro-sleep. He made inappropriate successive throttle increases, and the train speed increased to 44 mph. He failed to sound the horn at two crossings, ignored successive approach and stop wayside signals, did not dim his headlight as he passed the head end of an eastbound freight moving in the opposite direction on the adjacent siding. More importantly, he failed realize that the oncoming freight might not be fully off the main track. Two minutes later he collided with the middle of the eastbound consist34. NTSB investigators noted the engineer “remained sufficiently alert to make train control inputs yet [was] unable to respond to vitally important signal indications. [This] could be explained by the fact that making such inputs and manipulating the alerter are highly practiced, nearly reflexive, motor responses that require only lower level cognitive effort. During the engineer’s transition from wakefulness into the normal perceptual disengagement of unintended sleep, his capacity for information processing would have been severely compromised. Thus, he could have been able to continue the reflexive control activities, while being unable to perform the higher level cognitive tasks of extrapolating information from the signal indications.” The NTSB’s interpretation of the Macdona engineer’s behavior during micro-sleep episodes is supported by clinical descriptions of “Automatic Behavior Syndrome (ABS)” [26] common among patients who complain of excessive daytime sleepiness for various medical reasons35. In ABS, periods of automatic behavior last from seconds to hours, and have been polysomnographically correlated with repetitive micros-sleep periods. “The episodes typically involve the continuation of an activity that does not require extensive skill…The state will develop more easily if the patient is doing a monotonous task…An example is driving an automobile for more than a few miles….The patient is usually fighting against a feeling of drowsiness, and becomes less aware of his actions as performance deteriorates…Simple answers to simple questions [may appear normal] but attempts at complex answers are abortive and inappropriate. Actions which do not require skill will be performed satisfactorily albeit in a semi-automatic way; however if a sudden and well-planned decision is required, the patient will be unable to adapt appropriately to the new demand. Amnesia is a very common characteristic…A patient cannot remember what has happened during these episodes, though he may have some images like a “broken movie.. The notion of time is completely annihilated…patients may think that a very few seconds or minutes have elapsed when sometimes several hours have passed.” [26]. It has been suggested that automatic behavior is an admixture or rapid oscillation between waking and non-REM sleep states. [27] There is enough wakefulness to perform complex behavior, but not enough for conscious awareness of them [28].   The above is quoted from the following link starting at page 20: <a href="http://mvl.mit.edu/MVLpubs/OmanLiu_AlerterTechnologyAssessment_2007.pdf">http://mvl.mit.edu/MVLpubs/OmanLiu_AlerterTechnologyAssessment_2007.pdf</a>
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