I woke up with sore nipples, what could be wrong?

Nipple pain: Some women experience pain of nipples when stressed or cold due to vasospasm (raynaud’s of the nipple). Allergies to deodorants, lotions ; soap can cause pain. Eczema or psoriasis can lead to nipple pain. When the nipple is engorged it can cause pain. Hormonal changes can cause (puberty, pms, period, pregnancy ; breast feeding). Thrush or bacterial infections can lead to pain. Friction against.