The term A PERIOD OF SLEEPLESSNESS can be described by two crossword solutions: INSOMNIA (8 letters) and TOSSING (7 letters). INSOMNIA is a sleep disorder characterized by difficulty falling asleep, staying asleep, or both. It can cause significant distress and impairment in functioning. TOSSING and turning is a common symptom of INSOMNIA, as it is the physical act of struggling to find a comfortable position in order to fall asleep.