Certainly not alcohol, and coffee contains caffeine that could keep you awake. We recommend tea. Although the regular black tea leaves contain more caffeine than the same weight of coffee, that caffeine is more difficult to dissolve with hot water than coffee. So brewed tea contains less caffeine than brewed coffee. The best tea to drink at night is chamomile tea which induces sleep. Green decaf tea contains theanine, an amino acid that has calming effects.