Where the head goes the body will follow.
Excessive head movement can disrupt your freestyle alignment. I often see swimmers look up, look down, and from side to side while their face is in the water. The most harmful culprit is rolling the head to the non breathing side.
Try this: upon returning your face to the water after a breath, aim to stop your head movement once it is in line with your spine (image 2).
When I see the artwork or logo on the side of a swimmers cap on their non-breathing side it clearly indicates excessive head movement (image 3).
Next time you are in the pool, focus on your head position and repeat a simple mantra of “breathe, center” or“breathe, straight”, returning your head to be in line with your spine after you take a breath. For now simply focus on keeping the head as straight as possible when swimming. You can also try swimming with a snorkel. A snorkel can offer great feedback if you roll your head excessively because it will be difficult to keep it in your mouth.
Lastly, I have seen swimmers who normally demonstrate little head movement resort to excessive head movement when sprinting, thinking it will provide extra OOMPH. It doesn’t work.
Minimize your head movement and swim fast!