Alamak, ini common banget masa ada adik baru! Biasanya anak sulung jadi excited atau anxious, so tidur jadi delayed. A few of my mum friends noticed their older ones became restless at night, and one swear by creating a "special routine" just for kakak, maybe 15 mins of quiet time with you alone before bed, atau cerita pasal apa yg dia buat esok, makes them feel secure lagi. Try juga reduce screen time an hour before, and kalau susu dia dah habis, mungkin dia just needs that extra cuddle time with you, bukan kena more activities. Hang in there, usually it settles once they adjust to having a sibling!