Sentence:  She wakened in sharp panic, bewildered by the grotesquerie of some half-remembered dream in contrast with the harshness of inclement fact, drowsily realising that since she had <WSD>fallen asleep</WSD> it had come on to rain smartly out of a shrouded sky. 
Meaning of the word marked with <WSD> tags:  To pass from a state of wakefulness into sleep.