Sleep technology has moved well beyond the white noise machine on your nightstand. Sleep earbuds now pack active noise cancellation, sound masking and biometric sensors into something small enough to wear through the night. For anyone who tracks recovery metrics or fine-tunes their sleep environment, this category raises some worth-exploring questions. How well do these devices actually cancel noise? Can they survive a full night of side sleeping without discomfort? And is the sleep data they produce worth paying attention to? The technology is advancing quickly and the res...