What is a common result of low norepinephrine levels?

Low norepinephrine levels are commonly associated with sleep disturbances. Norepinephrine plays a critical role in the regulation of arousal, alertness, and the body's response to stress. When its levels are decreased, it can lead to disruptions in sleep patterns, often resulting in issues such as insomnia or excessive sleepiness.

In contrast, other choices focus on positive outcomes such as increased alertness, improved mood, or enhanced energy levels, which are typically linked to higher norepinephrine activity. Understanding this relationship helps highlight the importance of norepinephrine in maintaining mental and physical well-being, especially related to sleep and wakefulness. Sleep disturbances are a clear indicator of low norepinephrine, making this the correct answer.