Feet falling asleep/numbness

My feet frequently fall asleep/go numb during my runs. I just got a new pair of brooks ghost - the same brand and type I’ve been running in for 2-3 years, and I keep the laces loose and also sized up a half size, so I don’t think its because of feet swelling/not having enough room in the shoe. I’m wondering if it’s my form or if I’m hitting some nerve to make my feet go numb. Would love any insight into this!