How do I stop checking my phone at night and sleep better?

The most effective thing is to physically leave your phone in another room or at least far from your bed so it's uncomfortable to reach. If it's really hard to break the habit, turn on night mode and disable all notifications an hour before sleep so you're not tempted. The main thing is to understand that there's usually nobody texting you at night anyway, and you can check everything important in the morning - this really helps you calm down and fall asleep faster.