Unisom Sleep Gels Nighttime Sleep-Aid Soft Gels Liquid-filled soft gels leave no chalky taste behind like some other pills. Proven to be safe and non-habit forming. Reduces natural urge to stay awake. Helps to sleep soundly. Works by blocking the effects of a naturally occurring neurotransmitter, the body makes called histamine. When histamine is reduced, experience drowsiness, which allows to fall asleep faster and stay asleep longer.