What mental state might the inability to sleep reflect?

An inability to fall asleep or stay asleep might be caused by high anxiety or stress.

Emotional or mental distress puts the brain and body on a sort of "high alert." For this reason, people may have a difficult time falling asleep when they are anxious. Even if someone wants to relax and go to sleep, high levels of cortisol and adrenaline caused by stress can make this difficult. Adrenaline in particular, sometimes called the "fight or flight" hormone, primes our body and mind to act quickly in stressful situations.

A vicious cycle develops when stress interferes with someone's ability to sleep. First, the anxiety makes it difficult for someone to wind down and rest. A lack of rest then puts more stress on the mind and body, driving up those levels of hormones I mentioned before. Poor sleep creates more stress, which creates worse sleep! 

When someone finds that stress is interfering with their sleep, they should take action to try to break the cycle. Avoiding caffeine late in the day, creating a bed time "ritual" to train the brain to relax, and developing effective coping strategies can help to remedy this problem.