[Zack The Ripper]

IR flashes don't have a high enough wavelength to cause a disturbance to a NOD. A 300+ lumen LED at close range however is a different story. That will flare out most NODs for a split second, probably enough to give you that second of distraction, but not very long, even at close range.

However: Let's not forget that most people use monoculars. While wearing a NOD monocular both eyes eventually train to the monocular (simply the reflex of eye focus) regardless if it is over the left or right eye. While the weak eye is trained on the NOD it is not focused directly ahead, however a bright light source will confuse the focus of the weak eye not behind the NOD. The human eye as a reflex will want to train on the best/brightest light source in the dark; this is easy to prove simply by walking in the dark and having someone shine a bright light at you unexpectedly. Your eyes (and head depending on the angle) will automatically snap onto the direction of the source, and then, obviously if the source is too powerful for your eyes to adjust/focus quickly you squint/look away/etc.
People wearing a NOD are always focusing on that monocular for their vision and in most cases are using IR lasers to aim their weapons. If you are able to create a light source distraction at close range bright enough to break that focus from the monocular for a second or two and cause that confusion of "what the hell is that?", then it is an effective tool.

The trick is creating a source bright enough that strobes in the right fashion to do so. It also has to be pretty close. You would have to have many high output LEDs focused in all directions to achieve this.