What is a common finding in patients with restless legs syndrome (RLS) during a sleep study?

In patients with restless legs syndrome (RLS), a hallmark finding during a sleep study is an increase in leg movements, particularly during the transition to sleep or throughout the night. This condition is characterized by an uncontrollable urge to move the legs, often accompanied by uncomfortable sensations. As these patients attempt to fall asleep, they frequently exhibit periodic limb movements, which can lead to disrupted sleep. The increase in leg movements is a key indicator in diagnosing RLS during polysomnography, as it reflects the condition's intermittent involuntary movements that can severely affect sleep quality.

The other options either do not directly relate to the primary symptoms observed in RLS or represent findings that are not typically linked with the condition during sleep studies.