Sleep makes you strong, makes you feel good. It is an important element of human flourishing and well-being, both subjectively and objectively. Sleep is necessary for a healthy and balanced life. Your body and your brain are active when you sleep. We need to sleep long enough (quantity) and well enough (quality) to function well during waking hours. Nearly all physiological and behavioral functions in humans occur on a rhythmic basis, which in turn leads to diurnal rhythms in human performance capabilities. Sleepdex is dedicated to raising awareness of sleep issues and encouraging people to take sleep seriously.
About Insomnia - types, causes, solutions
Sleep Disorders - apnea, restless legs syndrome, narcolepy, and many more
Circadian rhythms - the cycles of the day and night
Tools for sleeping - bedding, medicines, etc.
Fun stuff - naps, deep sleep, mythology of sleep
Most adults need around seven or eight hours of sleep every night to function well. Although many people claim they require less, doctors who study sleep find only 10% require significantly more or less sleep. A chronic lack of sleep and untreated sleep disorders may be factors in the development of cardiovascular disease, obesity, and diabetes.
"Sleep rock thy brain" – Shakespeare, Hamlet
Sleep is an active behavior. Your body and your brain are active when you sleep. Biochemical and neurobiological functions take place all night long. Contrary to popular belief, the brain does not "shut down" during sleep.
In the sleeping brain neurons oscillate between two states. They are either sending out electrical signals similar to those observed when the brain is wake, or they are “off”, when they stop firing. (On an EEG the waking brain produces low-amplitude, high-frequency fluctuations, sleep shows up as high-amplitude, slow-frequency waves.)
Even when the person is awake, some neurons or clusters of neurons switch off, as they are when the brain is asleep. The longer the person is awake, the more likely any neuron is likely to go into this sleep state. This has been shown in rats. This local sleep partially explains microsleeps, dormiveglia, and the decline in measures of performance when a person has been awake for too long.
The orexin system is important in arousal. It also seems to be activated (becomes stronger) by sleep deprivation. This increase in orexin levels may allow the animal to get by in period of short sleep, such as emergencies. Some scientists believe the orexin system – or at least its activation during sleep deprivation – is a recent evolutionary development which led to an animal such as a human to maintain wakefulness for 16 hours before getting sleepy.
Mammals sleep like humans for the most part – the sleep can be divided into light sleep, deep sleep, and REM sleep. (There is some suggestion that dolphins don’t have REM, at least the way humans do.) Most mammals sleep in a polyphasic manner. Perhaps there is more sleep during certain periods of the day or night – diurnal animals sleep at night in general - but the overall pattern in polyphasic. Primates, including humans, sleep uniphasically.
Evolutionary biologists speculate that predation and fear of predators has influenced the development of sleep patterns across species. Carnivores tend to sleep more than herbivores. The range of mammalian sleep length is considerable, though, with armadillos and opossums sleeping 18 hours a day and horses and giraffes sleeping less than 3 hours per day. Horses are known as work animals that take a lot of what humans ask from them, but it is true that horses need little sleep.