From time to time I ask certain clients to keep a journal to keep track of their symptoms. For people with symptoms that are subjective, or are variable day to day, a journal can be be a good tool to quantify how often the symptoms are severe.
Every case is different, and everyone's symptoms are different. So a journal is not for everyone. But for some disability applicants with fibromyalgia, chronic fatigue syndrome, migraines, vertigo, chronic pain, depression or anxiety, a journal can really help.
Usually these claims are decided at steps 4 and 5 of the sequential evaluation. Furthermore, these impairments do not fit well into the Social Security physical RFC format, because on a given day, a claimant may be able to perform all the requirements of light work. The next day, however, the same claimant may be unable to get out of bed due to pain secondary to the impairment.
The most likely route to a favorable decision for such a claim is that the administrative law judge determines that for several days each month you will be unable to work due to your impairment. As a result, the judge rightfully concludes that you are unable to work on a regular and continuing basis, and therefore qualify for Social Security disability benefits (see Social Security Ruling 96-8p).
You can help the judge make this determination by keeping a journal, so that you have an accurate record of how many "bad days" you have each month due to your impairment.