Which of the following is NOT typically a cause of insomnia?

Regular exercise is not typically a cause of insomnia; rather, it often benefits sleep quality and overall health. Engaging in physical activity regularly can help regulate sleep patterns and improve the body's natural sleep-wake cycle, often leading to better and more restful sleep. Many health professionals promote exercise as a preventive measure against insomnia, as it can help reduce stress and anxiety levels, which are common contributors to sleep disturbances.

In contrast, the other options, like jet lag, poor sleep hygiene, and health conditions like anxiety, are well-documented factors that can disrupt sleep and lead to insomnia. Jet lag occurs due to changes in time zones, affecting the body’s internal clock. Poor sleep hygiene encompasses habits and environments that do not promote restful sleep, such as irregular sleep schedules or excessive screen time before bed. Health conditions, especially anxiety, can lead to racing thoughts and unrest, making it difficult for individuals to fall asleep or stay asleep. Therefore, regular exercise is distinguished as a positive influence on sleep rather than a cause of insomnia.