that is what i thought when i had my test so early, i won't be awake at the time .. but i got my test in the first test i had in the morning all others where in the evening .. 

In the morning, one is more relaxed and more presence of mind .. unlike in the evenings when you ming is stressed of the day's work and thinking about taking  the test..

Also . you get use to the qatar style of sleep while you drive"-)