Hi... You are talking about various types of anxiety disorders and various types of depression. The symptoms may vary from very overt to very latent. It is not wise to make out on your own for yourself, even if you are a Psychologist or a Psychiatrist. It is always better to consult another professional.
In general, any major change to a person's natural routine — sleep, diet, activity, weight, etc. Any signs of excessive happiness, sadness, irritability, negativity, or even to much positivity, can be a sign of an underlying condition. Increased screen time, work overload, over/under performance, increased or decreased social/personal contact, etc. all may guide towards an underlying conflict or some mental health issues.
In case of depression, by definition, any major symptoms continuing for more than 2 weeks may be a significant ground for a diagnosis. But all these signs and symptoms are to be considered against a general reference to a person's psyche and life experience. There cannot a be standard below which we can say all humans are depressed or a common point above which all humans are happy.
The experience of happiness/sadness is a very unique personal experience for all human beings. One person may not be happy receiving a Nobel prize and another person may be happy receiving a Google internship. Both of them may be normal or depressed based upon the reference to their personality, environment, and experience of life on a daily basis.
No one else can put a label on how we are feeling inside. It has to come from within.
Next Steps
Consult a Psychologist.
Interpersonal Guidance and Counselling using Existentialist Approach is required.
Health Tips
Mr. Gunjan Maithil
Senior Psychologist
Cell: nine six seven one three zero three one three four
Website: https://gunjanmaithil.wixsite.com/therapy
App: http://wix.to/fECHB08?ref=cl