Sleep

For example, the reason why they slept by day but awoke at night
remained unclear. Even enveloped by darkness in a secret chamber that
blocked out all possible light, a vampire’s body grew rigid with the coming
of that unseen dawn, their heart alone continuing to beat as they fell into
death’s breathless slumber. Despite a concerted effort at explanation
spanning thousands of years and investing the essence of every possible
field of science—ecology, biology, cerebral physiology, psychology, and
even super-psychology—the damned couldn’t shed a bit of light on the true
cause of their sleep. As if to say, those who dwelt in the darkness were
denied even the rays of hope.

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