Nap

, on a patio in Costa Rica A nap is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours or as a means to supplement before or after loss of sleep. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one period. There are multiple different types of naps depending on what the user's desired outcome may be or time constraints they may have, and for years, scientists have been investigating the benefits of napping, including the 30-minute nap as well as sleep durations of 1–2 hours. Performance across a wide range of cognitive processes has been tested, and naps have been shown to have various cognitive, physical, and psychosocial benefits.

, on a patio in Costa Rica]] A nap is a short period of sleep, typically taken during daytime hours as an adjunct to the usual nocturnal sleep period. Naps are most often taken as a response to drowsiness during waking hours or as a means to supplement before or after loss of sleep. A nap is a form of biphasic or polyphasic sleep, where the latter terms also include longer periods of sleep in addition to one period. There are multiple different types of naps depending on what the user's desired outcome may be or time constraints they may have, and for years, scientists have been investigating the benefits of napping, including the 30-minute nap as well as sleep durations of 1–2 hours. Performance across a wide range of cognitive processes has been tested, and naps have been shown to have various cognitive, physical, and psychosocial benefits. ===Sleep inertia=== The state of grogginess, impaired cognition and disorientation experienced when awakening from sleep is known as sleep inertia. This state reduces the speed of cognitive tasks but has no effects on the accuracy of task performance. The effects of sleep inertia rarely last longer than 30 minutes in the absence of prior sleep deprivation. ===Potential health risks=== A 2016 meta-analysis showed that there may be a correlation between habitual napping for more than an hour, and having an increased risk for cardiovascular disease, diabetes, metabolic syndrome or death. There was no effect of napping for as long as 40 minutes per day, but a sharp increase in risk of disease occurred at longer nap times. No causal relationship was established: the link may be to do with people taking a longer nap in response to the pre-existence of other risk factors. Habitual naps are also an indicator of neurological degradation such as dementia in the elderly, as reduction in brain function causes more sleepiness.

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