According to German researchers; summer sleep problems can drag into fall since it takes up to 5 weeks after the hot weather ends for the brain to start producing adequate amounts of sleep-inducing melatonin. The lettuce leaves contain lactucarium, a natural sedative and muscle relaxant that can help you drift off within 30 minutes of your first sip. To make the tea, chop 2 whole romaine lettuce leaves and let simmer in 1 cup of water for 20 minutes.