Even though her parents insist that a high school sophomore should be in bed by 9:30 on weeknights, Nadine finds it hard to get to sleep until at least 11:00. This is likely due to an increase in her levels of:

Melatonin

Explanation: melatonin in the body is a natural hormones that helps in the regulations or coordination of the cycle of our sleeping and waking. It is found in the pineal glad and it is more active during night time than day time.

Teenagers most especially has different time of sleep they sleep mostly late during weekends and sleep early during weekdays.our body needs sleep so as to function properly and most times our body is also adapt to some times that we sleep. Melatonin is usually release in the body gradually around 9pm in the evening where it initiate sleep but in some people, it is when the hormones is release in an increase dose that they can fall asleep thereby shifting the time to about 11pm or 12pm before the person can fall asleep for quick sleep, melatonin supplement are used.