Yes micro-sleep (or microsleep) is a real phenomenon that is well documented in both the mainstream and scientific literature and can be verified by EEG. There is also evidence to support that people are sometimes not aware when this happens.
With regards to the phenomenon itself, the BBC said that,
Of 1,000 drivers it interviewed, 45% of men admitted to micro-sleeping
while driving, as did 22% of women. But what does this mean?
Micro-sleep is an episode of light sleep lasting five to 10 seconds.
The brain goes to sleep involuntarily and it is more likely to happen
in a monotonous situation. People wake suddenly, often with a sharp
jerk of the head.
"Your eyelids start drooping and you start to lose contact with
reality," says Prof Jim Horne, director of Loughborough University's
Sleep Research Centre. "You're asleep for a few second, then wake up,
often with a jolt."
Which is similar to a report by ABC News,
Sleep researchers at the Liberty Mutual Research Institute in
Hopkinton, Mass., estimate that every day 250,000 Americans drive
According to National Highway Traffic Safety Administration figures,
more than 6,000 people are killed every year in vehicle accidents
blamed on an exhausted driver behind the wheel. That's second only to
drunk-driving fatal accidents and ahead of those attributed to driver
distraction, which includes texting.
These figures are also reported by highway safety administrations and researchers such as those in Texas, during symposiums, and finally the NHSTA reports their research on this topic under the heading "Drowsy Driving" which encompass micro-sleeps.
To further complicate the matter, there has been recent research into local sleep that can occur during period of wakefulness, as summarized by Science Daily,
Researchers at the University of Wisconsin-Madison have a new
explanation. They've found that some nerve cells in a sleep-deprived
yet awake brain can briefly go "off line," into a sleep-like state,
while the rest of the brain appears awake.
"Even before you feel fatigued, there are signs in the brain that you
should stop certain activities that may require alertness," says Dr.
Chiara Cirelli, professor of psychiatry at the School of Medicine and
Public Health. "Specific groups of neurons may be falling asleep, with
negative consequences on performance."
Until now, scientists thought that sleep deprivation generally
affected the entire brain. Electroencephalograms (EEGs) show network
brain-wave patterns typical of either being asleep or awake.
Most of these articles and research indicate that those surveyed are either unaware or deny the extent of their fatigue so it is reasonable to conclude that those experiencing it are unaware of the event. Furthermore, the research cited into local sleep demonstrates that in rats it can occur even when the subject appears awake.
To further expound upon the question of if people are aware of micro-sleep episodes, the following discussion was found:
Most drivers involved in sleep-related vehicle crashes usually deny
having fallen asleep, with evidence pointing to the crash being
sleep-related coming from other sources. Possible reasons for the
denial could include fear of procession and loss of insurance
indemnity. It is possible, however, that the person genuinely had no
memory of having fallen asleep, with studies showing that drives who
fall asleep typically deny having been asleep if awoken within a
minute or two (30). It is very likely, however, that drivers falling
asleep at the wheel were aware of the precursory feeling of sleepiness
even though they may not remember this after the crash (30).
An older text on the "Neurobiology of Sleep and Memory" contains a discussion about micro-sleep in the broader context of amnesia that can point to the biological explanation for the denial,
Another question concerns what happens to the information during this
abnormal state and why patients deny any memory trace of the events.
During micro-sleep episodes a lack of perception may exist, which is
responsible for a non-acquisition of information. The results from the
LSVT seem to confirm this assumption. But micro-sleeps are very short
events and the absence of perception during these periods can only
account for a small amount of the total amnesic period. Another
component must also play a role in the existence of the amnesia. Our
patients obviously present a retrograde amnesia and if we combine the
results of our pilot study on students with the finding on our patient
population, one could suggest that a certain amount of information
stored in the "short-term" memory pool cannot be switched to the
long-term pool because of successive micro-sleep events.