YES. Staying up late is very unhealthy for you. Our body naturally follows something called a circadian rhythm which allows us to feel tired at night and awake in the morning. By going to bed later than normal, you are shifting your body’s internal clock, causing your body to function differently. This causes a shift in your hormone balance, can cause you to feel tired and groggy the next day, and ultimately is not good for your health. Teenagers and young adults need the most sleep, 7-9 hours a night, which is crucial for their growth and development.
Another reason why it is unhealthy to stay up late is because of your eating habits and digestion. When you stay up later you will generally eat more food since normally you would be asleep. This is also bad for your digestion because generally if you are up late and are eating before bed you might have some problems with digestion. Naturally our body likes to be awake and alert when we eat so that it can be properly digested. Going to sleep right after consuming food is unhealthy because our food just sits in our stomachs.
Conclusion: Staying up late is very unhealthy and will have negative side effects.