Efficacy and Safety of Zolpidem-MR Administered Over a Long Term Period as Needed for Insomnia (ZOLONG)

Evaluation of the Long-Term Efficacy and Safety of Zolpidem-MR 12.5 mg Compared to Placebo, When Both Are Administered Over a Long-Term Period "as Needed", in Patients With Chronic Primary Insomnia

The primary objective of the study is to evaluate the hypnotic efficacy of zolpidem-MR 12.5 mg in comparison with placebo, when administered over a long-term period, on an "as needed" basis, in patients with chronic primary insomnia.

Secondary objectives of the study are to evaluate the drug taking behavior over a long-term period and the clinical safety and tolerability of zolpidem-MR 12.5 mg in comparison to placebo administered over a long-term period, on an as needed basis.

Inclusion Criteria:

• patients with chronic primary insomnia

The investigator will evaluate whether there are other reasons why a patient may not participate.