Nap

Benefits to napping

Learning and memory

Research suggests that shorter, habitual naps after instruction offer the most benefits to learning. The benefits to alertness show no change based on duration of the nap for combating post-lunch dip, even for naps as short as 10 minutes. Napping enhances alertness in young adults and adolescents during afternoons' performances, which affect efficiency. Additionally, pre-teens who nap regularly during the day demonstrate better sleep at night. In younger children, napping increased drowsiness even while improving memory recall.

For students of all ages, napping during the school day showed benefits to reaction time and recall of declarative memory of new information, especially if the naps remain in slow-wave sleep, i.e. less than an hour in length.

Some studies have shown that a 60–90-minute nap can be more effective than caffeine alone for memory and cognition.

Cognitive capacity

In adults, a causal association has been found between habitual daytime napping and larger brain volume. Brain volume normally declines with age, and is associated with neurodegenerative disease. Earlier studies have shown benefits of napping for cognitive performance for healthy adults.

Alertness and fatigue

The circadian cycle plays a role in the rising demand for daytime naps: sleepiness rises towards the mid-afternoon, hence the best timing for naps is early afternoon. Twenty- to thirty-minute naps are recommended for adults, while young children and elderly people may need longer naps. Research, on the other hand, has shown that the benefits of napping depend on sleep onset and sleep phases rather than time and duration.

Prescribed napping

It has been shown that excessive daytime sleepiness (EDS) can be improved by prescribed napping in narcolepsy. Apart from narcolepsy, it has not been demonstrated that naps are beneficial for EDS in other sleep disorders. For idiopathic hypersomnia, patients typically experience sleep inertia and are unrefreshed after napping.

For healthy individuals in need of cognitive or emotional improvement, prescribed naps may be beneficial. However, excessive napping, especially in adults with other health conditions, may be linked with negative outcomes and should be approached holistically and with caution.

Negative effects of napping

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.

Naps across the lifespan

The need and benefits of napping vary across different age groups since sleep patterns and requirements across a person's lifespan vary with time.

• Infants and young children: Regular naps are crucial for growth, development, and mood regulation. They contribute significantly to memory consolidation and learning processes.
• Adolescents: Napping can improve mood, alertness, and academic performance, especially when nighttime sleep is insufficient. Some research suggests that the biological changes marked by puberty in adolescents are highly correlated to a later sleep onset time, lower sleep efficiency, and other sleep pattern changes that might point to why adolescents, especially older adolescents, may require more naps.
• Adults: Short naps can enhance cognitive functions, mood, and alertness. However, longer naps may lead to sleep inertia and could be associated with health risks if they disrupt nighttime sleep. Adults requiring frequent daytime naps might have underlying sleep conditions, such as sleep apnea, that might need medical attention.
• Older adults: As sleep efficiency decreases with age, sleep patterns in older adults may shift towards napping more frequently to maintain performance without detriment to nocturnal sleep. Evidence shows that older adults with chronic health conditions may take naps to offset fatigue from their comorbidities rather than fatigue based solely on their age.

Best practices

How long and when a person naps affects sleep inertia and sleep latency: a person is more likely to benefit in terms of those two points when they sleep moderately in the afternoon. According to research, the degree to which a person experiences sleep inertia differs in different durations of nap. Because sleep inertia possibly results from awakening from slow-wave sleep, it is more likely to happen when one has a longer nap. Sleep inertia is less intense after short naps. Sleep latency is shorter when a nap is taken between 3 and 5 pm, compared with a nap taken between 7 and 9 pm.

According to The Sleep Foundation, Psychology Today and Harvard Health Publishing, these are the best practices for napping:

• Setting up a sleep-friendly environment
  • Dark room
  • Quiet atmosphere
  • Only using the bed for sleep
  • Limiting electronic use prior to sleep
• Understanding physical needs
• Setting an alarm in order to prevent the negative impact of sleep inertia and sleep latency