Taking a nap is a roll of the dice; sometimes, you rise refreshed, and other times, you wake more exhausted than before you closed your eyes.
There’s a reason for that discrepancy, according to Thomas Michael Kilkenny, DO, director of the Institute of Sleep Medicine at Northwell Staten Island University Hospital, who told The Post that following some specific guidelines will ensure you’re taking the most nourishing nap possible.
In fact, there’s a magic number of minutes when it comes to getting the most out of your midday snooze.
“Napping, when designed properly, can improve our daily lives,” said Kilkenny, who previously shared his four rules for the perfect nap.
T”his is especially true if we do not get enough good quality sleep at night. Sleep restriction (not getting enough sleep) has significant negative effects on feelings of sleepiness, motor and mental performance and mood, as well as on metabolic, hormonal and immunological function.”
The Centers for Disease Control and Prevention estimates that 35% of US adults don’t get enough sleep, and research has established that this lack can lead to impaired cognitive functioning, high blood pressure, diabetes, heart and kidney issues, fatty liver disease, memory loss, depression and increased inflammation, which can lead to different kinds of chronic health conditions and diseases.
A slumber deficit can also weaken immunity, meaning a higher likelihood of catching a cold or the flu.
Sleep restriction has also been linked to visceral fat, the belly fat that builds up around vital organs and has been tied to metabolic disease and insulin resistance.
Continued loss of sleep is a “catabolic stressor,” which means it could lead to metabolic dysfunction and loss of muscle mass.
And perhaps worst of all, improper rest can make you age like Gollum.
However, naps can offset some negative consequences, as long — or short — as they follow a few guidelines.
A study published last year in the journal Sleep Health found that taking a quick nap during the day may correlate with larger brain volume.
Our brains tend to shrink as we age, but the brains of habitual nappers were found to be large enough to offset up to 6.5 years of aging.
Napping has also been shown to boost creativity, improve parenting, and increase joy. Experts have even coined a word to describe the bliss state reached after a brief doze — nappiness.
How long is the perfect nap?
Kilkenny notes that when it comes to a siesta snooze, brevity is key.
“Naps should be relatively short, lasting no more than 20-30 minutes. Shorter naps of around 10 minutes can also be helpful,” said Kilkenny.
“Sleeping longer can trigger the effects of sleep inertia. This is the feeling of continued sleepiness upon awakening.”
Kilkenny explained that sleep inertia can cause disorientation, depressed motor skills, poor balance, difficulty communicating and reasoning, moodiness, impaired memory, and irritability.
Sleep is categorized into five stages: wake, stage 1, stage 2, stage 3, and REM.
According to Kilkenny, the physical and mental instability associated with sleep inertia “occurs immediately after napping, but its severity can be decreased by avoiding long naps that may result in awakening from stage 2 or N2, deep non-rapid eye movement sleep.”
The body can enter this stage of sleep, also known as non-REM, about 30-45 minutes after nodding off. As the name implies, this state of deep rest is characterized by the absence of rapid eye movement, dreaming, or bodily movement.
“When this happens, it is difficult to jump out of a deeper stage of sleep and become fully awake. Our brains want to continue to finish the deeper sleep before waking up.”
Kilkenny shared that a short period in stage two can be restorative to mind and body, but entering stage 3 can cause serious sleepiness.
“When awakened from lighter sleep stages, sleep inertia can be suppressed,” he said. “The negative effects of prolonged napping can depend on nap duration, amount of prior sleep deprivation, and the time of day when napping occurs.”
Sleep experts say 1 p.m. to 3 p.m. is the sweet spot for short-term shut-eye as the body experiences a natural circadian dip or a dip in energy levels, making it an ideal time for napping.
