The Cortisol – AM/PM Test measures cortisol levels at two different times of day to provide information about the body's daily cortisol pattern. Cortisol naturally changes throughout the day, typically reaching higher levels in the morning and declining toward evening. Measuring both morning and afternoon or evening levels can offer useful information about this rhythm. Testing may be considered when evaluating concerns involving stress, energy, sleep, or hormone regulation. A Cortisol – AM/PM Test should be interpreted in context because factors such as medications, illness, sleep patterns, and stress can influence cortisol levels. Professional interpretation is recommended for meaningful evaluation.