Hypoxia, or hypoxiation, is a pathological condition in which the body as a whole (generalized hypoxia) or a region of the body (tissue hypoxia) is deprived of adequate oxygen supply. Variations in arterial oxygen concentrations can be part of the normal physiology, for example, during strenuous physical exercise. A mismatch between oxygen supply and its demand at the cellular level may result in a hypoxic condition. Hypoxia in which there is complete deprivation of oxygen supply is referred to as anoxia.

Hypoxia differs from hypoxemia in that, in the latter, the oxygen concentration within the arterial blood is abnormally low. It is possible to experience hypoxia and have a low oxygen content (e.g., due to anemia) but maintain high oxygen partial pressure (pO₂). Incorrect use of these terms can easily lead to confusion, especially as hypoxemia is among the causes of hypoxia (in hypoxemic hypoxia).

Generalized hypoxia occurs in healthy people when they ascend to high altitude, where it causes altitude sickness leading to potentially fatal complications: high altitude pulmonary edema (HAPE) and high altitude cerebral edema (HACE). Hypoxia also occurs in healthy individuals when breathing mixtures of gases with a low oxygen content, e.g. while diving underwater especially when using closed-circuit rebreather systems that control the amount of oxygen in the supplied air. A mild and non-damaging intermittent hypoxia is used intentionally during altitude trainings to develop an athletic performance adaptation at both the systemic and cellular level.

Malcolm John "Mac" Rebennack, Jr. (born November 21, 1940), better known by the stage name Dr. John (also Dr. John Creaux, or Dr. John the Night Tripper), is an American singer-songwriter, pianist and guitarist, whose music combines blues, pop, jazz as well as zydeco, boogie woogie and rock and roll.

Active as a session musician since the late 1950s, he came to wider prominence in the early 1970s with a wildly theatrical stage show inspired by medicine shows, Mardi Gras costumes and voodoo ceremonies. Rebennack has recorded over 20 albums and in 1973 scored a top-20 hit with the jaunty funk-flavored "Right Place Wrong Time", still perhaps his best-known song.

The winner of five Grammy Awards, Rebennack was inducted into the Rock and Roll Hall of Fame by singer John Legend on Monday, March 14, 2011.

Born in New Orleans, Louisiana, United States, Dr. John's Acadian ancestry traces back to the imperial territory of Alsace-Lorraine. He claims that his lineage took root in New Orleans sometime in the early 1800s. Growing up in the Third Ward, Dr. John found early musical inspiration in the minstrel tunes sung by his grandfather and a number of aunts, uncles, and cousins who played piano. He did not take music lessons before his teens, he only endured a short stint in choir before getting kicked out. His father, the owner of an appliance store and record shop, exposed him as a young boy to prominent jazz musicians like King Oliver and Louis Armstrong. Throughout his adolescence his father's connections enabled him access to the recording rooms of burgeoning rock artists such as Little Richard and Guitar Slim. From these exposures he advanced into clubs and onto the stage with varying local artists, most notably, Professor Longhair.