What are the main duties of a Mental Health Nurse in a hospital setting?

I was recently an inpatient in a private psychiatric hospital. Apart from doing a 'ward check' ( to make sure you are there), blood pressure, temp, and hand out meds - thtat was IT. I know they are not social workers or psychiatrists but..... I know they have to do patient notes and paper work, but for goodness sake surely there more they should be doing to assist a patients wellbeing?..

Psyche nurses, while they are doing your vital signs,talk to you, document your conversations for other professionals to add to their evaluations during team conferences, all patients put on a different face to each person they interact with, they also document your actions, reactions, your affect, ( are you happy, sad, any facial expressions). They document what they see, and thier observations are shared with the team to be evaluated. You the patient are in the hospital to start working on making your self well or stable which ever your Dx allows for, as you know some things are controlled not healed. You are not their only patient, however anytime you are in their sight you are on their 'radar' and your behavior or lack of is being monitored quietly if you knew you were being observed so much you would not act as your normal self who is the person they are being paid to keep track of so well you are not totally aware of it.
You have group and private therapies, activeties all which are being assessed, all which you are more aware of and can pretend in or not, sometimes the nurses unobtrusive observations are what help the team know if you are trying to snow job them or are more ill than you want them to know. So if you truly thought the nurses were doing nothing but taking vitals and passing pills they were doing a great job.
Good Luck on your mental health, I hope what ever sent you to a psyche hospital is fixable and you work hard and be well.

There isn't much else they CAN do other than be cheerful and nice.

What you listed is their primary duties. They chart all this information and let the psychiatrist, psychologist and social worker know what is happening. Their information is very important and they see the patients more than the rest of the staff so their input is very important.

Not really. Nurses on the psych units do just that. There is, however, much more behind the scenes work that the patients dont see (extensive charting, care planning and implementation, admissions, ect...) The nurses do 1:1 time with their patients and make associated notes to assist the social workers and the psychiatrists in doing what needs doing to stabilize the patient and to re-integrate them back into their respective communities. If there was more that you felt that you needed, any nurse would have helped you if you asked. Otherwise, you are on your own and for good reason. Unlike other areas of the hospital, the focus is on getting you stabilized and back home with outpatient treatment. This is do to several things: the abuse suffered in the old mental asylums and the lack of continued insurance payments. Good Luck.