People occasionally develop numbness/tingling sensation in their limbs because of the pressure while sleeping, sitting crosslegged on the floor, squatting etc. This stays for a while and improves once the pressure is released. TIA is like a stroke which gets corrected in a while- like you get paralysis in some portion of your body, which improves on its own. It can happen anytime, not just while sleeping. Given your age 27, and the symptoms occuring only during sleep, I would feel it's because of pressure. I would suggest you to take care of your sleeping position. But if you get the same symptoms even during regular time, I would advise you to get complete stroke workup.