You should go to bed and wake up at the same time each day, even on the weekends. This will help your body to get into a sleep rhythm and make it easier to fall asleep and get up in the morning. Sleeping late, even during the weekends, is unhealthy for your body, as you will find that you will have a harder time falling asleep that night. Your body will have already gotten all its needed sleep earlier, and will refuse to go to sleep. To improve your sleep, try eating a carbohydrate-rich snack shortly before you go to bed. Warm milk, herbal teas, and foods that are high in  tryptophan, such as yogurt and tuna, are also good choices. Avoid overeating, or you may be kept awake by indigestion. Avoiding fluids within one hour of going to bed will reduce the likelihood that you will need to get up and go to the bathroom, or at least minimize the frequency. Try to go to the bathroom right before bed to increase your chances of being able to sleep undisturbed. The blue light emitted by televisions and electronic screens interferes with sleep by suppressing melatonin production. For better sleep, shut devices off an hour before bedtime.  Avoid other screens as well, like cell phones and tablets. If you must watch television before bed, don't do it in your bedroom. Try to designate your bedroom as a place for sleeping. Try to stop working at least one hour (but preferably two or more) before bed. This will give your mind a chance to unwind so you can go to sleep feeling calm, not hyped up or anxious about tomorrow's deadlines. Avoid staying up later than you normally would to work or study. Instead, try to plan ahead so you will have time to do these things earlier in the day. Instead of watching television or working, do an activity that will help you wind down after a long day. The key is to find something that makes you feel relaxed, then repeat it each night to help you release the day's tensions.   Read a pleasurable, slow-paced book. Try to avoid reading a suspenseful book, as you could end up reading for hours,...

TL;DR in Indonesian:
Jangan mengubah waktu tidur. Konsumsilah makanan yang tepat. Perhatikan asupan cairan Anda. Jangan menonton TV tepat sebelum tidur. Kesampingkan pekerjaan Anda. Lakukan sesuatu yang merilekskan sebelum tidur. Mandilah dengan air panas, berendam, atau sauna sebelum tidur.