Heliotropin is an aromatic compound that is reported to possess stress-reducing properties. In this study, we investigated the subjective and objective effects of heliotropin on nocturnal sleep. First, we used a sleep inventory to examine the effect of heliotropin on subjective sleep quality in daily life. Over one week, the aroma of heliotropin or a placebo was presented during sleep to 34 women, aged 23 to 39 years. Heliotropin significantly reduced sleepiness and improved refreshment at awakening for 13 participants who suffered from insomniac symptoms. Next, we recorded a polysomnogram for four consecutive nights for 12 university students, aged 18 to 25 years, who had previously reported that they took more than 30 min to fall asleep. After two adaptation nights, the aroma of heliotropin or placebo was presented on either the third or fourth nights. Heliotropin significantly decreased sleep stages 1 and 2 and significantly increased stage 4 and REM sleep. These results suggest that the aromatic compound heliotropin subjectively and objectively improves sleep for those who have difficulty in falling asleep.