Aiyo, I totally get it, trimester 1 insomnia is real and super stressful, apalagi kalau mual-muntah lagi. Honestly, a lot of mums say the nausea and hormones are the biggest culprits, so magnesium might help some people but it's worth checking with your doctor first before starting any supplements.
What I've heard works better for most is sticking to the basics: tidur dan bangun on the same time every day (even weekends!), buat bilik gelap and sejuk, and avoid heavy meals atau caffeine after noon. Some mums swear by light pregnancy exercises or gentle stretches in the evening, helps relax the body so you're actually ready for sleep instead of lying there wide awake. My neighbour said even 15 minutes of slow walking during the day made a big difference for her sleep quality.
Also honestly, sometimes the mual itself is what's keeping you awake, so makan lighter, smaller portions spread throughout the day rather than big meals. And try not to stress about the sleep itself; paradoxically, worrying about insomnia makes it worse!
Definitely check with your OB/midwife though, they can rule out anything else and suggest what's safe for your trimester. Hang in there, mama, ini temporary!