addiction risk in taking 1/2 mg klonopin 3 times a week for sleep

The short version: 0.5 mg three times a week is a real dependence risk, not a trivial one, and the sleep benefit is the part nobody has proven.

The honest answer is that no retrieved study tested your exact pattern, so I am reasoning from mechanism and from what the records do show. Clonazepam is a long-acting benzodiazepine, and the withdrawal literature is built on people who took it daily for weeks or months, not three nights a week [2][3]. Intermittent dosing is genuinely different: in mice, alternate-day clonazepam avoided the tolerance that daily dosing produced [1]. That is the strongest argument in your favor, and it is animal data.

The risk that remains is dependence itself. In a Quebec survey of older adults, about 1 in 4 used a benzodiazepine and roughly 1 in 10 of those users were dependent [4]. Those were mostly regular users, not intermittent ones, so treat that as a ceiling, not your number. The mechanism is the same either way: your brain adapts to the drug's presence, and stopping abruptly can produce rebound anxiety and insomnia that feel like your original problem getting worse [2]. That rebound is what pulls people from three nights a week toward every night.

What would settle your question is a study of intermittent low-dose use in insomnia patients over months, tracking dependence and taper difficulty. I did not find one here. The closest thing to a safe exit is structured: combining a slow taper with cognitive behavioral therapy for insomnia got 85% of older adults off benzodiazepines versus 48% with tapering alone [5]. That is the path I would point you toward rather than indefinite intermittent use.

My call: three nights a week at 0.5 mg is lower risk than nightly use, but it is not risk-free, and I would not run it indefinitely without a plan to stop. Confidence: low, because the exact pattern is unstudied.