A few possibilities come to mind: gastro-intestinal distress such as esophageal reflux, food allergies/intolerance, excessive gas production.
But, there could also be what is called "reverse sneeze" by older veterinarians (and I would never consider my youthful self older...), and this is a stimulation of the nerve bundle in the retropharyngeal or back area of the throat. The dog stars to snort and suck air at the same time, not dangerous but pretty dramatic. No treatment for this manifestation.
And possibly your little dog is becoming overheated and is simply panting off the excessive heat. Or your dachshund is waking herself from a dream. Or post-nasal drip....
Now what to do? If this isn't demonstrated in my office then I tell my clients that for the next week give the pet a light snack before bedtime: if no improvement, then a child's antihistamine at bedtime (usually Benadryl--in this case no more than 12mg) for a week. If no improvement, then it is time for a veterinary visit.
Dr. Van Lienden
Dr. Raymond Van Lienden DVM
The Animal Clinic of Clifton
12702 Chapel Road, Clifton
Virginia, U.S.A. 20124