If you see droplets on the plant at night/early in the morning, it may simply be guttation, which is a harmless and normal process in plants.

Here is a link that might be useful: Guttation

If the 'sap' isnt sticky, it's probably guttation as mentioned above. However, a sticky persistent residue is likely honeydew deposited by insects.

I would suspect scale insects rather than aphids for plants growing inside the home. Scale might not be recognized as pesky insect pests by the novice, but are the main contributor of honeydew. Look for little brown bumps along the stems and on the leaves. They can be scraped off easily, but don't move around as adults.

Aphids are absolutely visible to the naked eye....can't be missed.

Just home and thanks for the replies. The sap is definitely sticky. I'm not able to see anything that looks like scale and anything else for that matter that looks odd. The sap is mainly on the stems and on the underside of the leaves along the centre veins that run down the length of the leaf.

Any chance of some closeups of the underside of an affected leaf and some stems?

Thanks again. I didn't get around to taking pictures yet as I've been working. Finally above freezing today so I visited my favourite nursery which is mainly known for their houseplants. The owner was there who has been in business for over 40 years and as soon as I mentioned sap and the Money Tree (Pachira) she knew what I meant and said that it was perfectly fine and although it was occasional for the sap to appear, these plants are known for it. We looked at her Pachiras and sure enough there were some showing some sap. Maybe the time of year? Maybe a defence against predators? I find this quite interesting and will try to find some more info about this. Don't know what this occurrence would be called.

rosebuddy, this appears to be a normal feature on some plants.
I almost panicked the first time I was confronted by the sticky droplets on an Aglaonema.
Here is Link on the subject.