Which statement indicates that zolpidem has been effective for a client?

The statement "I have been sleeping better" indicates that zolpidem has been effective for the client because zolpidem is a sedative-hypnotic medication primarily used to treat insomnia. Its primary aim is to help individuals fall asleep and maintain a restful state throughout the night. When a client reports improved sleep quality, it directly reflects the medication's therapeutic effect, suggesting that they are experiencing the desired outcome of increased sleep duration and potentially better overall sleep quality.

The other statements do not directly communicate the effectiveness of zolpidem in treating insomnia. For instance, not experiencing side effects or needing other medications may be positive, but they don't specifically indicate that the medication is working as intended for sleep improvement. Similarly, feeling more awake during the day may be a consequence of better sleep, but it doesn't provide direct evidence of zolpidem's effectiveness in facilitating sleep. Thus, the client’s acknowledgment of better sleep clearly signifies the desired result of the medication.