Most vampires fall into a semi-conscious, trance-like state during the daylight hours that keeps them aware of things happening around it.

The vampire may only leave its resting place at sunrise, noon or sunset. This is clearly the vampire's time of greatest vulnerability since it is helpless when resting within its coffin. During the daylight hours, the vampire's powers are considerably weakened; although it should be pointed out they are still dangerous and certainly powerful enough to wipe out reckless vampire hunters.

Older and more powerful vampires do not require such rest; they only need to avoid direct sunlight.

Probably another Stocker’s exaggeration as vampires were known to hide during the day but no description was given about what they were supposed to do during that time.