True Neck Size for Dress Shirts

Are your dress shirts loose enough for your neck?
According to experts, a tight collar can squeeze the carotid artery and the pressure can impair your vision or make you feel faint. You can stop the constriction of the neck by loosening the tie and if you buy shirts off the shelf, make sure you know your true neck size.
Do not simply put a tape measure around your neck and judge the thickness. Instead, take a shirt with a well-fitting collar and spread the collar out flat and measure from the center of the collar button around to the far end of the other buttonhole. This yields your true neck size, though it may be larger than what the tags on your shirts say. Fabrics, especially cotton, shrink after repeated washings, dryings, and pressings. It's also a good idea to get shirts with collars that are half-size larger than your true neck size.