What Causes Confusion, Poor Memory And Impaired Muscle Coordination?

Around bedtime, 9-10 pm my wife begins acting strangely. 5 times in the last month she begins to talk much slower, walk much slower, fails to understand simply questions or requests. Her muscular coordination is somewhat impaired (fails to touch her nose with her finger when asked, usually touches her cheek under one eye or the other.) Condition lasts about 1-2 hours after which she has no memory of anything that is said or done during this episode. She is polite to me and our girls but I don t think she really knows who we are during the episode. Until about 1 month ago nothing like this had ever happened with her. Back in 2014 she had a TIA (numbness on one side for approx 1.5 hour) but she remembers all about it and never failed to remember it. We recently saw a neurologist and he assured us that these new episodes are not TIAs but are probably TGAs (Transient Global Amnesia). I can t find anything that would suggest this because one predominate symptom of TGA is repeating a phrase or action because of loss of memory of having just done that. This does not take place in any way with my wife. She just wants to sit down and go to sleep because she is so tired. She cannot do some simple tasks like check the water level in her CPAP or get the mask on while having one of the episodes. Again when the episode is over she has no memory of what was done or said during the episode. What could be causing these?