Generally for breakfast I eat a smoothie containing 8oz soy milk, 1/2 cup berries, 1/2 banana, and 1 scoop protein powder. Unfortunately, however, my blender is very loud, and I will soon be moving into a smaller apartment with someone who is a light sleeper. If I make my breakfast the night before, and then put it in the fridge for the next morning, what will the effects be? I'd be concerned the protein powder would settle and get grainy, or that the ingredients would separate and lessen the overall flavor of the drink.
I make smoothies every morning for my wife and myself (and have for over a year now), and when working out also added protein powder. The only difference between our recipe and yours is an inclusion of a few ounces of greek yogurt.
On the days when I knew the workout would run long (and potentially make me late for work), I was making them the night before with no problem. As yossarian said, as long as you make sure the protein powder is fully blended/dissolved you'll be fine. I've noticed no graininess/texture difference between night-before and morning-of.
The ingredients do separate a little overnight, but a quick shake or stir and they're back to normal.
I would say to try it and see how it works with your exact combination of ingredients.
Something to watch out for: my wife swears that sometimes, making them beforehand would cause a bit of a "sharp" edge to the taste of the smoothie - if this is true, my guess would be the interaction between the acid in the fruit and the base in the dairy. But, not being a chemist I can't speak to that. I can, however, say that I personally haven't noticed a difference based on whether it was made the night before or not.
I see that you're not using ice; I don't know if you're using frozen berries or not, but if you're used to a chunkier ice-like smoothie from frozen berries, you'll lose that texture of course.
I think you're probably right, the ingredients would settle / separate, however I bet you could fix that with a spoon and a stir. I can't talk to the protein powder, but if it fully dissolves, I'd think it would be ok. If it doesn't fully dissolve, try using a bit less of it. If you were using ice, it obviously wouldn't work.
So I think you're fine. Go for it!
I've read that some of the nutrients will start to break down the longer a smoothie sits around, but "If you want to prevent oxidation, blend in some lemon juice or part of a peeled lemon." (from smoothie-handbook) to minimize the loss.
Sometimes I make my kids smoothies the night before (also w/ whey protein powder - as well as frozen fruit, milk/juice and greek yogurt) - and pour it into ice cube trays. In the morning i pop 3-4 cubes in each cup and defrost in the microwave just til you can stir (its still pretty cold). It seems to last up to a week (you can mix and match too - i'll store them in baggies).