Ask the Expert: What Is “Good Sleep”?

The science of sleep is evolving. Sleep medicine doctors and researchers now know that the quality of your sleep affects more than your ability to stay awake throughout the day. Your sleep significantly impacts your overall health — from your weight and muscle coordination to your heart, lungs, brain, and immune function. Consistently poor or inadequate sleep puts you at risk for heart attack, car accidents, overeating, and interpersonal conflicts at work and with loved ones. Just one sleepless night can drag you down for days, negatively affecting your mood, memory, and focus.

If you have trouble falling or staying asleep, there are many ways to improve your sleep quality before asking your doctor about sleeping pills. Click here to learn how to fall asleep in minutes and how your phone may help lull you to sleep.

What is a good night’s sleep, anyway? As Kori Ascher, D.O., a sleep medicine specialist at the University of Miami Health System’s sleep center, explains, getting quality sleep is more nuanced than crawling into bed at the end of the day.

What happens while you sleep?

When you’re asleep, your body slows down, conserving energy, as it supports your immune and cardiovascular systems and promotes tissue repair and cellular growth. Your sleeping brain files and stores information in your memory, regulates hormones for sleep and repair, clears out waste, and reorganizes nerve cells to improve cognition.

The restorative power of sleep depends on your sleep architecture (like a map of your sleep cycle) and sleep continuity (uninterrupted versus waking up throughout the night). “All stages of sleep contribute uniquely to overall sleep quality,” Dr. Ascher says.

A complete and restorative sleep cycle includes all of the sleep stages:

• Rapid eye movement (REM) sleep is essential for mood regulation and memory processing.
• Non-rapid eye movement (NREM) stages N1 and N2 support sleep continuity.
• N3 (slow-wave sleep) plays a critical role in physical restoration, immune function, and memory consolidation.

Can you tell if you’re getting enough sleep?

“The American Academy of Sleep Medicine and the Sleep Research Society recommend that adults aged 18 to 60 years obtain six to eight hours of sleep per night on a regular basis to promote optimal health,” says Dr. Ascher. According to the U.S. National Heart, Lung, and Blood Institute, ongoing sleep loss (less than six hours of sleep per night) is linked to heart disease, kidney disease, high blood pressure, diabetes, stroke, obesity and depression.

If you’re getting enough restorative sleep, you should generally:

• wake up feeling refreshed
• be able to maintain a stable mood throughout the day (in the absence of a mood disorder)
• be able to maintain your attention (in the absence of an attention deficit disorder)
• experience steady, typical cognitive function (for you) throughout the day
• feel energized and alert throughout the day (not excessively sleepy)
• not doze off unintentionally
• be able to function socially and at work without fatigue or reliance on napping or caffeine overuse

Signs of sleep loss include:

• excessive daytime sleepiness
• inability to mentally focus
• difficulty learning new things/processing information
• bodily fatigue
• emotional instability/crankiness
• lack of coordination
• compromised motor and driving skills/reaction time
• lack of energy or stamina for exercise
• increased hunger and cravings for sugary foods and carbohydrates.

Some people need more sleep than others.

Some people claim to feel sharp and well-rested on less than six hours of sleep, while others have determined that they need at least nine hours of sleep to feel their best during the day. “This interindividual variability in sleep need is influenced by genetic, environmental, and behavioral factors,” Dr. Ascher says.

“However, short sleepers (those who consistently feel fully functional on less than six hours of sleep) are rare,” she says. “This phenotype is often due to a specific genetic variant in the DEC2 gene. Most self-reported short sleepers are chronically sleep-deprived with sleep insufficiency syndrome.”

Needing close to nine hours of sleep to feel optimal is within the normal range and more common among younger adults and those recovering from an illness, traumatic brain injury, or surgery.

You can get too much sleep.

Oversleeping (more than 9 to 10 hours per night in adults) can actually leave you feeling groggy or fatigued the next day. “Excessive sleep may also disrupt circadian rhythms and alter homeostatic sleep pressure, leading to difficulty initiating or maintaining sleep in subsequent nights,” Dr. Ascher says.

If you frequently oversleep at night yet often feel tired during the day, this cycle may point to an undiagnosed sleep disorder. Hypersomnia is a condition marked by persistent, excessive sleepiness and fatigue coupled with prolonged periods of sleep that don’t leave you feeling rested. “Hypersomnia is often a symptom rather than a cause,” Dr. Ascher says, “as is seen with mood disorders, obstructive sleep apnea, chronic pain syndrome, and poor sleep quality.”

Alcohol and marijuana aren’t good sleep aids.

Alcohol can make you feel sleepy. More than a couple of drinks or a “nightcap” may even cause you to nod off unintentionally. That’s because “alcohol initially acts as a sedative, reducing sleep onset latency,” Dr. Ascher says.

“However, as it is metabolized during the night, alcohol leads to increased activation of the sympathetic nervous system and frequent arousals (waking up). Even moderate alcohol intake, particularly in the hours close to bedtime, has been shown to disrupt sleep architecture,” she says. “Specifically, alcohol suppresses REM sleep in the first half of the night and results in sleep fragmentation and lighter sleep in the second half.”

Similarly, acute low-dose “THC (the psychoactive ingredient in marijuana) may shorten sleep onset latency due to its anxiolytic (anti-anxiety) properties,” she says. This means that, along with the calming effects of marijuana, users may feel sleepy.

Unlike alcohol, cannabis has variable effects depending on the strain, dose, and chronicity. “However, chronic use and higher doses are associated with decreased slow-wave sleep and REM suppression,” Dr. Ascher says. “Upon withdrawal, users may experience REM rebound, vivid dreams, and sleep disturbances. The American Academy of Sleep Medicine does not currently recommend cannabis for the treatment of any sleep disorder.”

Even one sleepless night has its risks.

Sleeping very little, even for a single night, can impair your attention, working memory, mood, and reaction time.

“Sleep debt is cumulative and cannot be fully repaid in a single night of extended sleep,” Dr. Ascher says. “Recovery from partial sleep deprivation typically requires multiple nights of extended sleep to fully restore cognitive and physiological function. Even if you feel ‘back to normal,’ you may still be operating at a cognitive deficit. This can translate to slow reaction times leading to a motor vehicle accident.”

Help for poor sleepers: sleep disorders and chronic sleep deficits

Some adults rarely get sufficient sleep because they’re living with an undiagnosed or untreated sleep disorder.

“You may be chronically sleep-deprived yet unaware of your impaired performance because you’ve gotten used to it and adapted,” Dr. Ascher says. “Conditions like insomnia and circadian rhythm disorders may be present, even when overt sleepiness is not reported. The absence of fatigue and mental fog is suggestive, but not definitive evidence, of sufficient sleep.”

Your perception of how well and how much you’ve slept can be unreliable. There are many sleep tracking devices and apps available to monitor when you fall asleep, how frequently you toss and turn, and how much deep sleep you’re getting each night. Some of these products can help identify the relationship between your sleep patterns and other aspects of your health and lifestyle, such as alcohol consumption, exercise, stress, eating near bedtime, illness, and hormonal changes.

“While consumer sleep tracking devices can provide useful insight into your sleep patterns, clinical assessment of sleep adequacy can be effectively performed without them,” says Dr. Ascher. “But, many sleep stages cannot be measured accurately without polysomnography or validated actigraphy (used during medical sleep studies), reinforcing the importance of clinical evaluation when concerns arise.”

If you consistently find it hard to fall or stay asleep, often wake up feeling groggy and stay fatigued throughout the day, or fall asleep unintentionally during the day, you may be a good candidate for a sleep study. This clinical examination of your sleep architecture, breathing, and heart rate may reveal what’s preventing you from attaining deep, continuous sleep and why you feel unrested while awake. Effective treatments and strategies are available.

To learn more, contact the UHealth Sleep Center. Call 305-243-9999 (ZZZZ) or click here to request an appointment.

Written by Dana Kantrowitz, a contributor for UHealth.

Tags: Dr. Kori Ascher, hypersomnia, insomnia, sleep aids, sleep debt, sleep deficit, sleep study