During a home visit, the nurse assesses a client with Alzheimer's disease who recently started a new prescription for rivastigmine. The caregiver reports that the client seems to be thinking more clearly but is not sleeping well at night. Which action should the nurse take?

A. Rivastigmine is used to improve cognitive function in Alzheimer's disease and not specifically to promote sleep, so suggesting a medication change is not appropriate without further assessment. B. Insomnia can be a side effect of rivastigmine, especially when starting the medication. It is often temporary and should improve as the body adjusts. C. Withholding the medication or changing the dosage without guidance from the healthcare provider could impact the client's cognitive function and should not be done based on a single side effect. D. Increasing the dosage of rivastigmine is not a solution for insomnia and could potentially exacerbate other side effects.