Many factors affect memory more than most people are aware. Memory deteriorates with age, there's selective memory, but as of late people of all ages and backgrounds have reported an increase in forgetfulness without physical or emotional cause. Young people shrug it off while seniors worry about senility.
This is happening for the most part because souls are detaching from the grids as consciousness spirals out of the simulation that creates this illusion.
Let's take this to the loops in space-time of which some people are aware while most are not. As with all else in the simulation - they are accelerating.
This can lead to feelings of anxiety and a need to calm the mind. Proper diet, deep breathing, restful sleep, yoga and meditation are a temporary fix.
If you are missing time, you most likely have not been abducted by aliens, it's just your brain adapting to external changes.
Memory Index - Science and Pseudoscience