Bagsy, I would hazard a guess that your eyes are sluggish because the lower temperature may be causing them to temporarily be less flexible. Does the blurriness tend to go away after you have been up awhile and had a chance for your eyes to "warm up" and be exercised a bit? You might try a warm washcloth on the eyes for a few moments when you get up and then do some eye exercises where you focus far away, then close up, down, up, side to side, roll your eyeballs around, etc. and see if that results in your bluriness dissipating more quickly.