Wedding preparations are stressing me so much I find it hard to sleep. How do I calm myself?

Reduce what you are carrying, rather than just enduring the stress; a simple wedding is still valid and blessed. List all the tasks, then mark those that are truly needed, those that can be handed to others, and those that can be dropped. Set one time a day for wedding matters, and stop thinking about them after Isyak. Involve your future spouse and family fairly, because you do not need to be the sole manager. Before sleeping, take wudu and recite some short dhikr, because “in the remembrance of Allah do hearts find rest” (Surah ar-Ra'd 13:28). If poor sleep drags on for weeks, or you start losing your appetite and crying easily, see a doctor or counsellor. See mental health.