Anna was having trouble sleeping, often waking up in the middle of the night and being unable to go back to sleep. She had been under a lot of stress at work, and figured that stress must be the cause. She consulted a self-help book that said that drinking herbal tea was an effective method of stress relief. She began drinking one cup of herbal tea every night at 7pm. She noticed after a few days that she stopped waking up in the middle of the night. Which method of knowing has Anna NOT employed in her quest to fix her sleep problem (based on the information given)