Odors don't usually cause a person to wake up. Researchers have found that smell sensitivity changes throughout the day according to the circadian rhythm. In general, the sense of smell is strongest at dusk and weakest at night and in the early hours of the morning. With normal sleep, you may well be awakened by the smell of coffee or fried bacon, stimulating appetite and increasing levels of arousal.
According to a new study from Brown University, people can't rely on their sense of smell to wake up to the danger of a fire. You may be familiar with rosemary as an aromatic addition to your meal, but the benefits of rosemary go far beyond the kitchen. Studies show that rosemary can refresh and boost your mood, brain activity, and nervous system.
Aromatic salts(ammonium carbonate) have been used since at least the 17th century to revive a patient after fainting.
Yes, but only certain smells, if I remember correctly, are specifically about the smell of food and possible dangers. The smell of sulfur gas will wake you up, for example, because your body wants you to move before you die.