What is one common symptom of overtraining?

Inability to sleep is indeed a common symptom of overtraining. When an individual undergoes excessive physical training without adequate rest and recovery, their body can become stressed, leading to disruptions in sleep patterns. This can manifest as insomnia or difficulty staying asleep, which is often related to elevated levels of stress hormones like cortisol. Additionally, physical fatigue and mental exhaustion can interfere with the body's natural ability to relax and achieve a restful state, further compounding the sleep issues associated with overtraining.

In contrast, experiencing increased energy, heightened mood, or enhanced performance would typically be indicators of a well-managed training program where recovery is adequately balanced with physical exertion. These traits do not align with the physiological and psychological effects of overtraining, which tends to lead to fatigue and a decrease in overall performance.