What percentage of Magnesium is the Swanwick Sleep Magneisum Oil Spray? Sarah A December 27, 2017 01:10 Updated Follow 50% magnesium. Related articles What is Magnesium Oil Spray? How do I use the Magnesium Spray? Why is a spray the best way to take Magnesium? What's different about your Sleeping Mask? How are your glasses different from other cheaper glasses? Comments 0 comments Article is closed for comments.