I've had intermittent sleep disruption due to blockage/swelling of nasal passages for about 5 years. It comes and goes (but never for long) and seems to be worst at this time of year. I've never suffered from allergies, and this condition (which an ENT says is aggravated, but not solely caused, by a deviated septum) isn't accompanied by any classic symptoms of rhinitis--runny nose, mucous, etc. In fact, my nasal passages tend to be rather dry, except for low grade post-nasal drip, usually on the side that feels most blocked.
My spouse often reports that I begin tossing and turning around 2 AM, about 3 hours after I retire. By 3 or 4, I'm waking up every 15 min. or so, completely blocked on one side and barely able to breathe on the other. Another aggravating factor is that I end up sleeping on my back and then my tongue rolls into my throat, leading to snoring and a parched throat. On my worst nights, the broken sleep pattern begins as soon as I've drifted off, and I spend most of the night dozing and switching from side to side to clear blocked lower airway.
I've tried nasal irrigation with a Neti pot, Nasonex, Breathe Right strips, Sudafed, and breathing exercises. All have been effective at times, and all have failed me at others. Lately I've noticed a correlation between coffee consumption and bad nights. It may just be that coffee makes me more edgy and likely to be awakened by breathing difficulties, but caffeinated teas don't seem to have that effect.