I got up at 0300 hr, started at 0330 hr, picked up a friend, and drove for 4 hours. After meeting the friend, while returning, I experienced this microsleeping.
I saw a truck parked roadside during my drive, but didn't make any attempt to move away. Truck is seen, but no action taken. I was awoke. My friend sitting by the side tapped me and I came to full senses and drove the vehicle safely.
I wondered what happened to me, thought like is it sleep paralysis. Later, searched internet and found this state of awoke, but sleeping subconsciously is known as microsleeping. This arises due to fatigueness, stress, etc.
Remedies are, having good rest before start of journey, intermittent breaks or short duration rest periods like taking coffee, water, etc.
I sipped water during the driving.