In biology, dormancy refers to the state of reduced metabolic activity that many organisms enter, either when they are facing environmental stress (consequential dormancy) or when they are likely to face such stress (predictive dormancy). During the dormant phase, they reduce their metabolic activity, which, in turn, helps them conserve energy and survive despite the severe crunch of resources. When a chipmunk hibernates, it brings down its heart rate from 350 beats per minute (bpm) to as low as 4 bpm. How Does Hibernation Differ from Other Types of Dormancy? Though it has become synonymous to dormancy off late, hibernation, like aestivation, brumation, and daily turpor, is just a type of the broad concept that dormancy is. If it has become so popular, it is largely because of the fact that it is used by species that are quite popular. These include a whole lot of rodents, including chipmunks and groundhogs, as well as mammalian species like hedgehogs and bats. Before they go into hibernation, these animals eat a lot of food and store it in their body in the form of fat. Once they gain sufficient weight, they take shelter in a warm place where they will spend the rest of the winter in deep sleep. During this period, they reduce their heart rate by as much as 90 percent. There is no specific period of hibernation as such. It can go on for weeks and even months at times. Hibernation is further divided into two types: true hibernation and false hibernation. When we speak of animals going into deep sleep where they are not affected by sound or touch, it refers to true hibernation. As opposed to this, in false hibernation, the animal involved can easily wake up from its sleep. The bear is an apt example of animals that are false hibernators. In the end, while the processes involved are different, both true and false hibernation serve the same purpose, i.e., to help the animal survive harsh environmental conditions and the resultant food crunch.