Sleep latency, the time it takes to fall asleep, varies from person to person. Most healthy people fall asleep within 15 to 20 minutes of lying down. However, some people will fall asleep faster, and others may take longer. Experts estimate that 1 out of 3 adults in the United States suffer from limited sleep or sleep deprivation. There are many reasons behind this, but one reason may be due to difficulties falling asleep. Some medications, the bedtime routine, and the environment can all cause someone to stay awake long after going to bed.

Source: Sleep Foundation