How deep do you sleep?

An adult who is compelled to nap repeatedly during the day may have excessive daytime sleepiness if it persists chronically. It is characterized by persistent sleepiness and often a general lack of energy, even during the day after apparently adequate or even prolonged nighttime sleep.

Both sleep quantity and quality play major roles in many aspects of life, such as mental health, work productivity, and general wellness. Nearly 25% of individuals have sleep difficulties. Several aspects of sleep phenotypes, including sleep quality, have been demonstrated to be heritable.

Naps are short daytime sleep episodes that are evolutionarily conserved across diverse diurnal species ranging from flies to polyphasic mammals. In human adults, daytime napping is highly prevalent in Mediterranean cultures and it is also common in non-Mediterranean countries including the United States. Although napping seems to have an acute benefit on increased arousal in the setting of sleep deprivation, the long-term effects of habitual napping on chronic disease risk remain controversial.

Awakening is a physiological process that refers to transition from sleep to waking and a crucial event for humans. Ease of awakening is one of the important sleep-related phenotypes which has been extensively studied in sleep research.