It is important to distinguish between progesterone (the hormone our body makes) and the synthetic progestogens which form part of some HRT.
There is a huge amount of information about all of this in the menu, but the basic purpose of progestogens of any type, as part of HRT, is to protect the uterus from thickening (endometrial hyperplasia) which can lead to cancer. Any other effect on the body is immaterial - outside basic safety checks and trials before the progestins (ie synthetic progestogens) are marketed.
That's the first thing - many women just do not get on with the synthetic types which can cause side effects
Secondly - many women suffer from some form of pms during the second half of their menstrual cycle - which is when progesterone in the body rapidly rises and falls. Many women are affected both by the rise and fall, and some throughout the two weeks from the progesterone itself. It exerts physiological changes in the body which can cause adverse symptoms. For women who suffered from pms for the whole of the second half of the month - then even bio-identical progesterone in HRT will disagree with them.
Thirdly - unfortunately there is a lot of information on the web about progesterone, much of which is designed to sell it, or promoted by private practitioners - mainly in US where people have to pay for health care. Any article which makes a blanket statement progesterone (makes women happy" is dubious in my book. You will find lots of threads (including recent ones) where this is argued so I suggest you search for these rather than rehearse again.
Prof Studd an eminent research gynaecologist treats women with post-natal depression, with oestrogen. You can read all about his work here:
http://www.studd.co.uk/I'm not sure about the calming either - I think a better description is that it has a sedative effect - which some argue is beneficial for some women in small amounts, but in others is so sedating as to lead to fatigue, lack of clarity of thought (cotton wool head), headaches, depression and similar.
Most women feel at their best during the first half of their menstrual cycle when oestrogen rises - so if anything this is really the "happy" hormone (although this isn't a word I would use!) - in the sense that it gives women vitality and zest for life.
Some women feel bad when they get to the oestrogen part of the HRT - initially - but this is often normal pmt, and is a result of progesterone withdrawal. Once it has gone from the system - there can be a few days of well-being - but this is one drawback of HRT for some women, that progresterone and eits effects are oftne felt for longer than on the menstrual cycle.
I agree it's confusing when you first start reading about it - so hope this helps.
Hurdity x