L-theanin to maintain sleep and melatonin to induce sleep?

Melatonin helps me fall asleep, even if I was wide awake 30 mins before. But the consequence is, I wake up 4 hours later and get stuck in a cycle of every 15 minutes falling back asleep and waking up until the alarm rings. I do take shilajit resin as well. Would L-Theanin be a potential solution to help me stay asleep? By the way, I really only need melatonin 1-2 nights a week if I have to go to bed early after having gone to bed way later the night before. This problem arises due to my work schedule unfortunately.