You might also try magnesium chloride flakes. Magnesium chloride flakes (such as Ancient Minerals flakes) are better absorbed than magnesium sulfalte ( Epsom Salts ), yet less costly than magnesium oil. Many people who love magnesium oil also keep magnesium flakes available, especially for baths. I think you can get magnesium flakes online from integratedhealth.com. Of course, if you find Epsom Salts work well with magnesium oil for you, then by all means keep it up. I would just suggest you take warm baths instead of hot baths. Warm baths open pores and allow maximum absorption of magnesium. Hot baths make you sweat and thereby block or reduce the uptake of magnesium (of any form).
As for your mind being awakened, magnesium chloride is known to help produce energy (ATP) in the body. It may be that while the magnesium is relaxing your muscles, it is helping to create more energized states elsewhere. That is, you may simultaneously be relaxed and energized (mentally). Magnesium oil supports improved sleep (by relaxing muscles and blocking pain receptors), yet also appears to reduce the amount of sleep people require. If your mind is active while your body is relaxed, you might consider an herbal remedy, such as chamomile tea, valerian, hops, or a nervine tincture (e.g., lobelia inflata) rubbed on neck and shoulders. Other alternatives might include acupressure, massage, meditation, or light yoga.