I was getting very worried with the shoulder pain that was occurring only at night whilst sleeping - a dull ache would come on.

After thinking long and hard it dawned on me one night that my shoulder was not covered and very cold and that perhaps it was the Air Conditioning and not the weight training.

Indeed, after changing the angle of the AC vents and ensuring the cold air was off my shoulder, my problem has gone away!

Relieved and happy!