Mental illnesses fall on a spectrum, and many come in waves/episodes. You do not have to have every symptom of an illness at all times to be diagnosed. Comparing a mental illness to a cold is a false equivalency imo. Coming from my perspective as [presently] high functioning bipolar 1, I have had episodes of crippling depression and mania ~

During severe depressive episodes, I am still able to get out of bed and go to work, all while feeling completely hopeless and suicidal at times. Everyone’s depression (or other illness) can present differently and affect them differently. You don’t have to be bed-bound to have MDD and it’s unfair to invalidate someone’s feelings bc they are able to function and put on a happy face and maintain their life.

There was a time when my episodes were so severe that I checked myself into a hospital after I lost my job and house. Currently I’m high functioning as my meds are right and I have been through lots of therapy, but I’ve never been more or less bipolar, just having symptoms present on various spectrums of varying severity.

Hope that perspective helps a bit. My point is just that everyone is different and every MDD patient, in this case, will have common symptoms but people can function on different levels.