Firstly James, thank you for your quite timely post. Timely because recently I've been curious to know the reason, if not answer, to the same question as you enquired about on this most useful and helpful forum.
So like you I found significant problems starting a stream after sleeping in bed, perhaps for just even only a few hours. Also I can experience similar difficulties in starting a flow after sitting for just a couple of hours too. However the two-hour sitting problem usually only occurs when I'm attending a show at the theatre. Attending the theatre means that for a number of reasons I'm somewhat restrictively 'boxed in'. Obviously when sitting for long periods and wanting to spend a penny at the theatre can be a problem but say at home, the 'boxed in' situation doesn't apply.
This difficulty starting a flow probably goes back to about 18 months ago and it's only been in recent months that I found taking exercise, such as a walk/stroll, does for whatever reason, helps to initiate a stream . I should also mention that for myself an even more noticeable improvement in both sleep length and lack of BPH symptoms, I personally find after playing 18 holes of golf. Unfortunately given the English weather I'm not able to utilise at this time of year…
So in in part it would seem one answer the initial enquiry of james87669 about poor stream start is related to lack of physical activity, which perhaps points to a relationship in causing muscle tightness and maybe in turn increased stress of the prostate? Which is thus possibly reduced when physical activity takes place? Just whether more physical activity is, as James mentions in his initial post, anything to do with "mind/body connections" I'm not entirely sure?
Perhaps it's worth mentioning that over a year ago in a private consultation with a urologist I mentioned my problem of difficulty of starting a flow, and was in no uncertain terms told by the urologist to take tamsulosin. Which although I was reluctant to do so, I did and it did to an extent help with initiating flow. However, chiefly due to the tamsulosin side-effects, a few months ago I gradually eased myself off tamsulosin. Fortunately since completely stopping taking it, so far, touching wood, apart from the experiences described above, starting a flow hasn't been a significant problem. What the reason is for the improvement I'm not altogether sure.
Perhaps though it's worth noting I have for the last 12 to 14 months significantly changed what I eat to an even more I believe healthy input of foodstuffs and liquid. E.g. for breakfast, I now eat a avocado, a papaya, home-made muesli made principally from various nuts, dried fruit, quinoa, sprinkled with organic wheatgrass powder, chlorella and/or spirulina. I have also installed a good four stage water filter and drink non-caffeinated herbal teas. If nothing else, since starting this change to a more natural food non-processed food diet (not that I ate much rubbish processed stuff before though), however since the change of diet, apart from finding it easier to start to a stream, I do have a good deal more energy than previously was the case. And this without having to put up with the well-documented side effects of tamsulosin!
Just out of curiosity, I wonder if some urologists or medics when dealing with patients that experience such urinary problems as described above, like poor stream start, if sometimes first they recommend the free more natural fix/workaround, i.e. such as, taking a stroll/walk etc for a few minutes.… And/or also do the medics enquire about their patient's diet. And if so, where appropriate, perhaps recommend to their patient/s to improve the diet? I'm tempted to ask if generally they don't mention these things, why is it?
Oh incidentally caringbah , yes I also find a much better flow when standing up as opposed to sitting down, I suspect gravity plays a role in the reason for this.