I just looked at the manual and there is no night-shot mode. Sorry about that. Have you tried cleaning the video heads? The information below is from the user manual.
"To ensure normal recording and clear pictures, clean the video heads. When X appears in the viewfinder or on the LCD screen in CAMERA mode or playback pictures are "noisy" or hardly visible, the video heads may be dirty.
(a) Slightly dirty
(b) Dirty
If this happens, clean the video heads with the Sony VS-25CLH cleaning cassette (not supplied). After checking the picture, if it is still "noisy", repeat tile cleaning. (Do not repeat cleaning more than 5 times in one session.)
Caution - Do not use a commercially available wet-type cleaning cassette. It may damage the video heads.
Note
If the V8-25CLH cleaning cassette is not available in your area, consult your nearest Sony dealer."
User Manual