The Architecture of a Good Night’s Sleep
By James B. Maas, Ph.D., Rebecca S. Robbins, and Sharon R. Driscoll
Maas Presentations, LLC and Cornell University
Given that we spend (or should spend) one-third of our lives sleeping, it’s alarming how little we know about our down time. Does it surprise you that 40% of laypersons and physicians think the brain shuts down and takes a rest when we fall asleep? In actuality, the sleeping brain is highly dynamic and, at times, even more active than when we’re awake. The sleeping brain plays a dramatic role in maintaining and regulating cardiovascular, gastrointestinal and immune functions. It also facilitates mental processes such as learning, memory, creativity and problem-solving. And it is the repository of your dreams. Adequate sleep is essential for performance and general health, and without it we risk daytime drowsiness, moodiness, irritability, anxiety, and a heightened risk of hypertension, obesity, type 2 diabetes, periodontal disease and cancer.
How do I know what happens when I sleep?
Imagine you’ve come to a state-of-the art sleep lab. (Most of them now look like 5-star hotels rather than scientific laboratories.) You’ve been hooked up to various devices that measure brainwaves, eye movements, muscle tension, body temperature, respiration, heart rate and hormonal activity. You might feel like Medusa with all these wires hooked to your body. But trust us, you’ll still be able to fall asleep. The technician will tuck you in and turn off the light, setting the stage for the theater of the night.
Many people believe that soon after going to bed they drift into deep sleep, remain there for some time, have an occasional dream, and then awaken for the new day. But there are several stages of sleep, each marked by significant changes in all those things being monitored and more.
The night is basically divided into non-REM (non-rapid eye movement) and REM (rapid eye movement) sleep. REM sleep is the period in which most dreams take place. Non-REM is also referred to as “slow-wave” sleep and is subdivided into several stages, earmarked by different brainwaves and purposes.
As you close your eyes, your brainwaves become slower and more regular. These alpha waves look like the teeth of a comb and signify a relaxed yet still wakeful state. This stage is akin to meditation. Next is the so-called Stage 1 period when you have theta waves for about 5 minutes as your breathing slows. The large muscles begin to relax. The transition to Stage 2 is sometimes marked by a fleeting sensation of falling, causing you to wake momentarily with a jerk (not referring to your spouse). During this period, you disengage from the environment and become blissfully unaware of any outside stimuli. Researchers believe Stage 2 is the beginning of actual sleep. It’s marked by spikes in brainwave activity called sleep spindles and K-complexes, which interrupt those previously regular waves. Stage 2 lasts 10 to 25 minutes, but you’ll return to it several times before daybreak, accounting for half of your night’s slumber.
Next comes Stage 3 sleep, which is characterized by slow brainwaves called theta waves. These are interspersed by even slower delta waves. You’ll spend just a half-hour here, but eventually it will comprise up to 20% of your total night’s sleep.
When the theta waves disappear, you enter Stage 4, the deepest sleep stage, which consists totally of delta waves. On your initial visit it lasts for 30 to 40 minutes. If aroused during Stage 4, you’ll feel groggy and disoriented. During this stage, blood pressure drops, respiration slows and blood flow to your muscles decreases. The secretion of growth hormone by the pituitary gland also peaks, stimulating body development and tissue repair. That’s why uninterrupted deep sleep of significant duration is especially critical for children and adolescents. And it’s why we sleep more when we’re sick. So in Stage 4, you’re completely out of it and at your most vulnerable. It’s the closest humans get to hibernation.
When do I dream?
After 30 to 40 minutes of Stage 4 sleep, you re-trace your steps through Stages 3 and 2. You’ve now been asleep for about 90 to 100 minutes. Then something astonishing happens. Instead of going back into Stage 1 or “twilight” sleep, your sympathetic nervous system becomes more active than it is in slow-wave sleep or even when awake. Blood flow to the brain, respiration, pulse rate, blood pressure and body temperature all increase. Your eyes dart back and forth under their lids, and you enter the highly active stage of REM sleep.
Fig 3. shows the architecture of a good night’s sleep. The dark blocks represent your time spent in REM sleep. Each REM cycle should be longer than the previous. Therefore, you sleep between hours 7-8 are critical for memory.
Here, messages from the brain’s motor cortex are blocked at the brainstem. As a result, muscles relax, and you’re unable to move. That’s why REM sleepers are described as having “an active brain in a paralyzed body.” It’s during the first part of REM that you experience your first dream of the night. Just like clockwork (because, in fact, this entire system is run by your biological clock), you enter REM sleep every 90 minutes throughout the night. When you’re sleeping adequately, you visit it 4 to 5 times, with each REM period being twice as long as the last. This is why your final few hours of rest are so important; they’re almost entirely REM sleep. If you’re asleep for 8 hours, you’ll have spent between 1 1/2 to 2 hours of the night in REM. Although dreaming can occur in all stages, about 85% takes place here. REM dreams are usually the most vivid and emotional. But REM just isn’t about dreaming. The previous day’s events are solidified into permanent memory traces, and sequences of learned skills (like a new golf swing) become muscle memories.
Our ancient ancestors viewed sleep as a mysterious, inert state that somehow played a role in survival. For them, sleep also made practical sense as a way to recuperate from fatigue and avoid nighttime dangers (i.e. being eaten by predators or falling off cliffs). Researchers are just beginning to fully understand the complexities of our sleeping selves and the powerful resulting impact on our waking lives.
We sleep for two reasons: First, our bodies run on cycles called circadian rhythms, of which the sleep cycle is one. Many of these cycles, such as heartbeat, blood pressure, respiration, metabolism and temperature, drop or slow during the sleep cycle. Mission Control for all these processes is a part of the midbrain called the suprachiasmatic nucleus. This is where your master body clock is located. If this nucleus is damaged or removed, you end up taking lots of short naps instead of having one long sleep period.
“If sleep has no purpose, it’s the biggest mistake evolution ever made.”
– Dr. Allan Rechtschaffen, a pioneer sleep researcher
Your circadian rhythms are set by various time cues called zeitgebers. Light is the most powerful one affecting sleep. Daylight wakes you up and darkness triggers the release of the hormone melatonin that brings on sleep. Noise and temperature can also play key roles in the regulation of your sleep schedule.
The second reason we sleep is because the longer we’re awake the greater our need for mentally and physically restorative sleep. It takes one hour of sleep to pay for every 2 hours of wakefulness. So we start to tire after being up for about 16 hours. Sleep debt is cumulative, which means the longer your deprive yourself of rest the more of it you’ll need to feel rested. How drowsy or alert you are depends on both your circadian rhythms and your sleep debt.
Does experiencing all the sleep stages every night really matter?
To be wide awake, energetic, psychologically, emotionally and physiologically at your best, you must play every movement of the symphony of the night. The problem is, many of us never get beyond stage 2 sleep, due to stress, aging or medications taken for other medical problems such as rheumatoid arthritis, hypertension or Type II diabetes. If you have having trouble sleeping after taking a new medication, ask your doctor if there are alternative prescriptions.
learning, remembering, creating and problem-solving?
Are you looking for a promotion? Trying to be more creative? Do you need to learn a new skill, or solve an old problem? Having an excellent memory and sharper insight will help you realize all these things, and the way to develop them is with adequate sleep. Learning ability, memory consolidation, creativity and problem-solving are all severely compromised by even a little sleep loss. New research shows that sleep and mental functioning are closely linked. But we didn’t need science to tell us that. Just look around at the successful, happy people you know. Are they the ones falling asleep at their desks, in meetings, or on the couch after dinner? To the contrary, those who are most productive and prosperous are the ones who are well rested (and can remember what they had for dinner the previous night). No doubt about it, the best brain food is a good night’s rest.
New finding: In almost every psychological experiment testing brain functioning, whether the test involves remembering pairs of words, tapping numbered keys in a certain order or figuring out the rules in a weather-prediction game, “sleeping on it” after first learning the task improves performance. It’s as if our brains squeeze in some extra practice time while we’re asleep. Sleep also seems to be the time when the brain’s two memory systems—the hippocampus and the neocortex—”talk” with one other.”
New finding: Experiences that become memories are laid down in the first two hours of sleep in the hippocampus. In the next four hours if a memory is to be retained it must be transferred from the hippocampus to a place where it will have physical permanence, the neocortex, the wrinkled outer layer of the brain where higher thinking takes place.
New finding: Stickhold and Wehrwein report that “Unlike the hippocampus, the neocortex is a master at weaving the old with the new. And partly because it keeps incoming information at bay, sleep is the best time for the “undistracted” hippocampus to shuttle memories to the neocortex, and for the neocortex to link them to related memories.” During the final 2 hours of REM sleep, the brain takes the information and repeatedly reruns it in a process called REM replay. So as you can see, any sleep longer than 6 hours helps in memory retention, but it takes 8 hours to fully incorporate learned material. That’s why you should make an extra effort to get a full night’s sleep after studying for an exam, rehearsing a presentation, or learning a new set of skills.
What’s the minimum amount of sleep I can get without my memory or learning be affected?
New finding: When it comes to memory, shortened sleep is bad news. No matter how intelligent you are, losing sleep means losing brain power. People who sleep less than 6 hours after learning new information show no improvement the next day, and those who don’t sleep at all perform only half as well on memory tests as their well-rested counterparts.
New finding: Here’s another interesting ripple: In order to prepare information for retention, the brain filters out what’s unimportant and solidifies the essentials, cross-referencing it with what’s already on file. This process of making connections between the new information and what was previously known is called memory consolidation. With inadequate sleep, you may be able to form new memories, but you won’t be able to retain them.
New finding: There is a direct correlation between REM sleep and learning efficiency. In fact, it seems the brain knows when it needs more consolidation time. Researchers studying people in intensive language programs have found that the amount of time they spend in REM sleep naturally increases the night after learning. As a result, they benefit from protein synthesis during REM sleep that increases the strength of the connections between brain cells and facilitates memory consolidation. (In other words, you should see these folks conjugate Arabic verbs!) During REM sleep, the brain is able to remove irrelevant details, creatively process the information, and even restore temporarily misplaced info that you couldn’t recall during the day. This purging and purifying removes poor information that is competing with pertinent material, thereby enhancing memory.
How much will losing an entire night of sleep hurt me?
It’ll have a profound impact. Physical movements will be sluggish, focusing will be difficult, and you’ll tend to “zone out” more frequently. New finding: Functional magnetic resonance imagery (FMRI) scans of brain activity in sleep-deprived individuals trying to perform even simple tasks show momentary lapses of functioning in several important regions.
Can sleep make me more creative?
Scientists, writers and artists have made discoveries or had insights while sleeping that changed the world. If it wasn’t for dreams, Mendeleev wouldn’t have completed the periodic table, Singer wouldn’t have invented the sewing machine, and the Nike brand name wouldn’t exist.
New finding: Research shows that subjects who slept adequately were almost 3 times more likely to gain insight into a problem than those who remained awake. Are you struggling with a challenging project or dilemma? If so, the solution might lie in 8 hours of sleep.
Is sleep more important before or after learning?
Both are crucial for memory retention. Loss of REM sleep prior to learning can result in a 50% reduction in the awareness of mental cues that help to establish memory. It also severely disrupts many duties of the hippocampus, which means you’ll have less of an ability to conceptualize, a duller reaction to negative events, and even a drop in your taste sensitivity (the sensory kind, not your preference for Barry Manilow).
Adequate sleep after learning, however, is most crucial. This is the only time that memory enhancement occurs. Research subjects who were deprived of sleep the first night after learning still showed no sign of improvement even after two subsequent nights of full sleep. In some cases, it has even been shown that people develop amnesia for the information learned. The simple truth is if you’re not sleeping after learning new information, you might as well spare yourself the trouble of learning in the first place. You need to remember to sleep, because you have to sleep to remember!
New finding: Other types of learning affected by sleep…
- Calling all singers! Sleep modifies brain activities involved in song production, allowing for improvement in pitch and tone.
- Athletic performance Motor skills can increase 19% to 21% after just one night of improved sleep.
How is brain activity altered when I don’t get enough sleep?
New finding: When you’re sleepy, your brain works in a completely different way than when it’s well rested. In fact, some parts don’t work much at all. FMRI images show that sleep-deprived brains have much less activity in the right hippocampus (memory center). Thus, losing sleep means losing memory, and not just for tomorrow—but for months afterwards.
New finding: By comparison, people who have slept a full night show increased activity in the cerebellum, a region of the brain responsible for speed and accuracy. There’s also decreased activity in their limbic system, which regulates anxiety. Yet with sleep loss, the amygdala, an area of your brain involved in rage and aggression, becomes more activated. So while the sleep-deprived are shuffling through life and have less control over emotions, the well rested are more alert and less stressed.
Sleep’s Golden Rules and Strategies.
Be sure you meet your sleep requirement every night, which for most people is between 7.5 and 8.5 hours every night. Establish a regular sleep/wake schedule, by going to bed and rising at the same time every night and day, including the weekends. Get one long block of nocturnal sleep, not a few hours at a time spread through the 24hr. period, and make up for lost sleep as soon as possible.
To keep wide awake and energetic all day long, follow these sleep strategies:
- Reduce stress in your life.
- Exercise daily, but not within 3 hours of bedtime. The best time to exercise is
between 5 and 7pm, not early in the morning or late at ngiht.
- Keep mentally active.
- Eat a proper diet.
- Stop smoking.
- Do not drink caffeinated beverages after 2pm.
- Avoid alcohol with 3 hours of bedtime.
- Take a warm bath before bed.
- Maintain a relaxing atmosphere in the bedroom.
- Establish a regular bedtime ritual.
- 11 Avoid trying too hard to get to sleep.
- 12 Limit your time in bed to when you are sleepy
- If you have insomnia for more than 3 weeks at a time, consult a sleep specialist.
- Learn to value sleep. Sleep is a necessity, not a luxury.
Dr. James B. Maas is a sleep educator/researcher who helped develop the Dr. Maas Sleep for Success line of pillows and comforters for United Feather and Down. He served for 48 years as professor, chair of Psychology and Weiss Presidential Fellow at Cornell University. He lectured about sleep to more than 65,000 undergraduates, several of whom are now sleep doctors.