- How Sleep Works
- Deep Sleep
- Getting Better Deep Sleep
- Sound Sleep or Deep Sleep?
- Understanding Sleep Cycles: What Happens While You Sleep
- Learn what is really going on in your body while you’re getting your zzz’s.
- Alzheimer’s and Sleep Problems: Insomnia, Oversleeping, Restlessness and Treatments
- Sleep and the Aging Brain
- Does Someone with Dementia/Alzheimer’s Need More Sleep?
- What About Excessive Sleep?
- Causes of Sleep Challenges with Alzheimer’s/Dementia
- Sleep During the Different Stages of Dementia
- Medications for Sleeplessness Associated with Alzheimer’s/Dementia
- Non-Medication Tips to Help with Sleep
- What Makes Someone a Heavy Sleeper (and How Do You Become One)?
- Can You Stop Being A Light Sleeper?
- What is light sleeping?
- Disturbed sleep
- Ambient sound
- I’m a Light Sleeper. This Is How I Finally Found Rest
How Sleep Works
Sleep is one of those funny things about being a human being — you just have to do it. Have you ever wondered why? And what about the crazy dreams, like the one where a bad person is chasing you and you can’t run or yell. Does that make any sense?
If you have ever wondered about why people have to sleep or what causes dreams, then read on. In this article, you’ll find out all about sleep and what it does for you.
Characteristics of Sleep
We all know how sleep looks — when we see someone sleeping, we recognize the following characteristics:
- If possible, the person will lie down to go to sleep.
- The person’s eyes are closed.
- The person doesn’t hear anything unless it is a loud noise.
- The person breathes in a slow, rhythmic pattern.
- The person’s muscles are completely relaxed. If sitting up, the person may fall out of his or her chair as sleep deepens.
- During sleep, the person occasionally rolls over or rearranges his or her body. This happens approximately once or twice an hour. This may be the body’s way of making sure that no part of the body or skin has its circulation cut off for too long a period of time.
In addition to these outward signs, the heart slows down and the brain does some pretty funky things (we’ll get to this later).
In other words, a sleeping person is unconscious to most things happening in the environment. The biggest difference between someone who is asleep and someone who has fainted or gone into a coma is the fact that a sleeping person can be aroused if the stimulus is strong enough. If you shake the person, yell loudly or flash a bright light, a sleeping person will wake up.
For any animal living in the wild, it just doesn’t seem very smart to design in a mandatory eight-hour period of near-total unconsciousness every day. Yet that is exactly what evolution has done. So there must be a pretty good reason for it!
Reptiles, birds and mammals all sleep. That is, they become unconscious to their surroundings for periods of time. Some fish and amphibians reduce their awareness but do not ever become unconscious like the higher vertebrates do. Insects do not appear to sleep, although they may become inactive in daylight or darkness.
By studying brainwaves, it is known that reptiles do not dream. Birds dream a little. Mammals all dream during sleep.
Different animals sleep in different ways. Some animals, like humans, prefer to sleep in one long session. Other animals (dogs, for example) like to sleep in many short bursts. Some sleep at night, while others sleep during the day.
Sleep has a profound effect on your brain, which we’ll examine in the next section.
Deep sleep is the most refreshing sleep, as subjectively described by people after they wake up. Unfortunately, the older we get the less deep sleep we get.
Deep sleep is stage 3 sleep (or stages 3 and 4 under the classification that includes a stage 4). On an EEG the voltage difference patterns over time show up as delta waves. This is also called slow-wave sleep to distinguish it from the fast-wave sleep of Stage 2. Deep, or heavy sleep, is so-called because it is more difficult to awaken people in this stage than in light sleep, and if woken suddenly from this stage, people have sleep inertia. People in deep sleep are less apt to wake in response to external stimuli than those in light sleep Sleepers in deep sleep move their bodies less than in light sleep, although more than in REM sleep. The restlessness of some sleepers that results in tangled-up bedding occurs in light sleep.
Deep sleep is a time of accelerated tissue repair. In growing children, this is a time of physical growth. Human growth hormone is released in the first deep sleep episode of the night, and the period is associated with rejuvenation. Common childhood sleep disorders such as nocturnal enuresis, night terrors, and sleepwalking happen during this period.
At some level, we crave deep sleep more than other types. If you stay up all night and go about your normal activities the next day, you have some sleep debt. But if allowed to sleep the following night as much as you need to feel refreshed, you will probably not double the time of your normal sleep. Rather, the normal sleep time is appended with an additional one-third to one-half of normal sleep period. So someone who normally sleeps 7 hours per night, may, after a missed night’s sleep, go for 10 hours before feeling back to normal. The interesting thing is the distribution of time among the stages during this recovery sleep. Pretty much all the lost deep sleep is recovered. The amount of deep sleep during this second night is twice what it is in a normal night. Lengths of REM and light sleep are lower. It seems that the body chooses to conserve slow-wave sleep as much as possible, and it more willing to sacrifice other stages of sleep.
An interesting experiment showed this desire for deep sleep bubbling up to the surface of waking behavior, however subconscious. Scientists monitored the sleep architectures of people with insomnia over an extended period of time. The insomniacs were not given access to their EEG results. The insomniacs were also given access to sleeping pills (benzodiazepines) and told they could take them if they felt they needed to. After nights when the people had lesser deep sleep, the subjects were more likely to choose to self-administer the sleeping pills. Stage 3 length was the single most important factor in predicting whether pills were taken. This suggests people have a feeling about their need for deep sleep.
Getting Better Deep Sleep
How can you get more deep sleep? Unfortunately deep sleep can be elusive, and there is no way to directly force your brain to spend more time in this stage. The best you can do is prepare the ground for it and hope you will be blessed.
One way to prepare the ground is to get a full night’s sleep every night. Sleep medications can help, but remember that all sleep medications modify your normal sleep architecture. None directly lead to more slow-wave sleep pe se. They tend to result in increased time in light sleep, but light sleep might lead to deep sleep. Exercise, particularly strenuous anaerobic exercise such as lifting weights, may provoke more slow-wave sleep, although the evidence on this is not firm. It is probable that some people react to exercise by getting more deep sleep and others do not. The fact that tissue repair is at its fastest in deep sleep and human growth hormone release peaks during this stage cannot be overlooked. Aerobic exercise helps some people increase the length of time in deep sleep. There is some evidence that raising the body temperature, such as by soaking in a hot tub, increases predilection for stage 3 sleep. The effect of the aerobic exercise may be due to that fact that it raises body temperature. There are problems with this theory, including the fact that people tend to sleep better in cooler temperatures, stage 3 does not start until more than an hour after sleep onset during which time the body cools.
Is some stage 3 sleep deeper than others? Maybe. Generally, deep sleep or heavy sleep is called that only in comparison to light sleep. There is some physiological evidence that the “depth” of the sleep varies while the sleeper is in Stage 3. Monitoring of the brain can show instantaneous depth of sleep within Stage 3,
However, it should be emphasized that this variation is measurable only within one person. It is true that some individuals appear to sleep deeper than others in the sense that they are less apt to be woken by external stimuli, but there is no way to tell if any given person’s sleep is deeper or shallower per se than others.
The loss of deep sleep with age
One of the unfortunate effects of age is that as we get older we spend less time in deep sleep. While healthy people in their 20s spend 20% of the night in Stage 3, a typical 40 or 50 year old spends only 10% in that stage. By age 70 or 80, it is down to less than 5%, and sometimes maybe 2%. Other factors notwithstanding, you could look at a person’s EEG chart for a night and get an estimate of how old they are.
Why is this decline unfortunate? Less deep sleep is not just a result of aging; it appears to at least partially cause some of the negative characteristics of old age. Weakness, decreased mental acuity, infrequent feeling of refreshment in the morning – these are all connected to less deep sleep.
Sound Sleep or Deep Sleep?
What does it mean to “sleep soundly”? What does it mean to “sleep deep”?
We can unpack these phrases with the scientific discoveries about sleep physiology of the past several decades.
“Sound” means whole and possessing integrity. Sound sleep is a description given to a night’s sleep that is satisfying to the sleeper. This is subjective, of course, and probably in relation to the sleeper’s experience of recent sleep. A sound sleep for a 50-year old might be described as troubling by a 20-year old. And that’s a good word for the opposite: troubling. The opposite of sound sleep is troubled sleep.
If we were to hook up a polysomnography machine to a person getting sound sleep, we would see few nighttime awakenings, no significant breathing problems, and a decent amount of time spent in both slow-wave deep sleep and REM sleep. “Decent amount” is subjective, but we can ballpark it as 90 to 120 min per night of deep sleep and 90 to 130 min per night of REM sleep for adults. (Too much REM is associated with depression. There doesn’t seem to be any such thing as too much deep sleep.) Sound also somewhat tangentially refers to the depth of sleep and how susceptible the sleeper is to awakening by noise. This concept is probably close to what people mean by sleep deeply.
At Tuck, we like to divide the night’s sleep into light sleep, deep sleep, and REM sleep (we didn’t invent these classifications.) Deep sleep is slow-wave sleep (called so because of the patterns of the EEG printouts) or Stage 3 sleep (according to one classification scheme) or Stages 3 and 4 sleep (according to other classification schemes).
What is the difference between quiet wakefulness and sleep? One difference is the ability or tendency to react mindfully to external stimuli. What is the difference between sleep and coma? Sleep is reversible; coma is permanent. But coma is also a state in which the subject cannot be awakened by shaking or loud noises, the way a sleeper can.
The depth of sleep is generally taken to mean how likely the sleeper is to be awakened from an external stimulus. Children are difficult to awaken not because they are lazy but because they are sleeping deeply. Even within a single stage of sleep (as measured by EEG) the depth varies as measured by sensitivity to acoustic stimuli. It has also been shown that people who have more “sleep spindles” on the EEG readings during a normal night of sleep have more tolerance for noise.
Also a hypnogram — the output of a polysomnogram — is typically printed so Stages 3 and 4 (the deep sleep) are shown lower on the page than Stages 1 and 2. This is just convention, but it further promotes the idea that Stages 3 and 4 are deeper sleep than the earlier stages.
By this measure, some people do sleep deeper than others. Compare two people in stage 3 slow-wave sleep and one may be easier to awaken than the other. Does this mean the deeper sleeper is getting more of the slow-wave sleep benefits than the lighter sleeper? No. The characteristics and benefits of different stages of sleep are relative to each other, not compared among people. Although some people are lighter or deeper sleepers than others (as measured by susceptibility to awakening), that doesn’t mean they are getting more or less out of sleep.
On an EEG measure, alpha waves (8-13 Hz) are a signature characteristic of the waking state. They significantly decline when the person falls asleep, but they do not disappear. Scientists have found that the level of alpha waves correlates with the depth of sleep. When alpha level is stronger, the sleeper is more susceptible to awaking from external stimuli.
Now what produces alpha waves is not understood. The thalamus section of the brain influences activity in the cortex that give rise to alpha activity, it appears, leading to a hypothesis that thalamus relays external stimuli to “cortical processing centers where it is capable of interrupting sleep”.
Understanding Sleep Cycles: What Happens While You Sleep
Learn what is really going on in your body while you’re getting your zzz’s.
Before the 1950’s, scientists used to believe that as people drifted off to sleep, their brains and bodies would go into “shutdown” mode, entering a passive state that allowed them to recover from the previous day. What researchers have since learned: Sleep is a whole lot more complicated, and it’s a much more active state than you might think. In fact, while you’re getting your zzz’s, your brain goes through various patterns of activity. It’s a predictable cycle that includes two distinct parts – NREM, or Non-REM sleep, plus a REM or “Rapid Eye Movement” cycle.
Check out what happens in your body during each phase of sleep:
Stage One: Within minutes (sometimes even within seconds!) of nodding off, your brain produces what are called alpha and theta waves and your eye movements slow down. This introduction to sleep is relatively brief, lasting up to seven minutes. Here, you are in light stage sleep, which means that you’re somewhat alert and can be easily woken. It’s during this stage of sleep that people often indulge in brief “catnaps.”
Stage Two: During this stage, which is also fairly light, the brain produces sudden increases in brain wave frequency known as sleep spindles. Then brain waves slow down. If you were to schedule a “power nap” you’d want to wake up after this stage of sleep.
Stages Three & Four: This stage is the beginning of deep sleep, as the brain begins producing slower delta waves. You won’t experience any eye movement or muscle activity. At this point, it becomes a little harder for you to be awakened, because your body becomes less responsive to outside stimuli. The brain produces even more delta waves and you move into an even deeper, more restorative stage of sleep next. It’s most difficult to wake up during this stage. This is when the body repairs muscles and tissues, stimulates growth and development, boosts immune function, and builds up energy for the next day.
Rapid Eye Movement (REM) Sleep: You generally enter REM sleep about 90 minutes after initially falling asleep, and each REM stage can last up to an hour. An average adult has five to six REM cycles each night. During this final phase of sleep, your brain becomes more active. This is when most dreaming occurs, your eyes jerk quickly in different directions (hence, the name!), heart rate and blood pressure increase, and breathing becomes fast, irregular, and shallow. REM sleep plays an important role in learning and memory function, since this is when your brain consolidates and processes information from the day before so that it can be stored in your long-term memory.
It’s important to note that these phases last for different durations at various ages; an infant’s sleep cycle will look different than that of an adult or elderly individual. On an average night, you move through the stages in a sequential fashion. Most non-REM sleep occurs early in the night and the length of REM periods increases as the night goes on. That’s why there’s a good chance you’ll awaken from a dream in the morning—hopefully, a sweet one!
Alzheimer’s and Sleep Problems: Insomnia, Oversleeping, Restlessness and Treatments
Last Updated: May 03, 2019
The night is lonely, dark, and full of unknown sounds and shadows. For someone with Alzheimer’s disease or another form of dementia, telling the difference between reality and a nightmare can be impossible. Imaging waking within an hour every time you fall asleep, confused, not knowing where you are.
Bad sleep at night means more difficult days. Anxiety and aggravation increase. And if a person naps while the sun’s up to account for a bad night, the result is sleeplessness after sunset and the terrible cycle beginning anew. Sleep is yet another complicated consideration for caregivers of loved ones with dementia. What can be done when it’s time for bed?
Sleep and the Aging Brain
Studies suggest that more than half of patients with Alzheimer’s or other dementia have issues sleeping throughout the night. And it can be paradoxical, as someone who seems tired during the day will suddenly, come nightfall, be restless and even wide-awake.
An unfortunate consequence of aging, even if the brain remains relatively healthy, is that sleep becomes harder. The quality of most people’s sleep gradually deteriorates as we age. Deeper sleep is important for mental health (some studies have suggested that someone who has difficulty sleeping is more at risk to develop Alzheimer’s), and the older we get the more difficult it is to fall into a state of deep sleep. While elderly people tend to sleep more, sometimes as many as 14 hours per day, it is rarely restorative deep sleep. They are more likely to wake for reasons including discomfort and having to use the bathroom.
Insomnia is much worse for people with dementia, many of whom cannot get more than an hour or two of continuous sleep before waking, often disoriented.
Does Someone with Dementia/Alzheimer’s Need More Sleep?
In short, persons with early to mid-stage Alzheimer’s or other dementias do not require more sleep than healthy individuals of the same age. However, in practice, the quality of the sleep they experience can be very poor. To accommodate for the poor sleep, many individuals will sleep more hours.
Someone with dementia is already suffering with an inability to process the surrounding world, but imagine adding drowsiness to the equation. Not getting enough sleep, even in healthy brains, causes tension and moodiness; in someone with dementia, the effects are magnified and devastating. Feeling tired provokes aggressive outbursts, and moodiness can reach the level of full-blown depression. Mistakes become more common, even dangerous, as an elderly person is much more likely to fall or suffer an accident after a bad night’s sleep.
Days obviously become more difficult after lousy sleep, as moodiness, anxiety and aggravation are more likely. Caregivers are advised, however, not to compensate for a bad night’s sleep by allowing a person with dementia to sleep throughout the day.
Our “circadian rhythms” are the physical and mental cycle of the day, incorporating wakefulness and metabolism. Also known as the “internal biological clock,” circadian rhythms are thrown out of whack by dementia as the innate sense of day and night is lost along with the ability to think clearly. The result is, at least, confusion—people with dementia can be confused about whether it’s day or night, even if they can plainly see whether the sun is up or down. For these reasons, working to maintain a sleep routine is important, despite the difficulties. (See tips below.)
What About Excessive Sleep?
Seemingly excessive sleep may be unavoidable. As symptoms of dementia become more severe, especially in the later stages of the disease, sleeping more during both day and nighttime is common. This is because as brain function deteriorates the body loses strength, turning simple actions, like merely listening and trying to communicate, into exhausting ordeals that sap strength.
It is also possible that medications, particularly antipsychotics and antidepressants, will cause side effects that include increased sleepiness.
If someone in the earlier stages of dementia is unexpectedly sleepier than normal, it is important to speak with a doctor. Difficulty sleeping, rather than excessive sleep, is much more common in early-stage dementia, and drowsiness may indicate something else is wrong, like infection or adverse reactions to medication.
Studies have indicated that Dementia with Lewy Bodies (DLB), a form of dementia associated with how the brain processes protein, has shown higher rates of drowsiness during the day than Alzheimer’s or other dementias. Tiredness in these cases can be unrelated to how well a person slept the night before.
Causes of Sleep Challenges with Alzheimer’s/Dementia
People with Alzheimer’s and other dementias lose their circadian rhythm, explained above as our internal sense of night and day. This means that even in the evening someone might believe it’s morning and therefore not an appropriate time to go to bed. Someone exhausted from a long day can lose the ability to understand when it’s time to sleep, and so despite a tired body sending signals craving bedtime, a dementia-racked mind will override those signals. The result of this is aggravation and anxiety. Wandering and even yelling at night is not uncommon.
There are other common reasons someone with dementia has trouble sleeping. As the sense of reality deteriorates, less lighting means more shadows can make the environment frightening. Restless leg syndrome, common for people with dementia, causes unpleasant crawling or tingling sensations and strikes typically during periods of rest, especially at night.
Another important factor for caregivers to consider is that their loved one may be sensitive to nonverbal cues indicating frustration at the end of a long day. It would be ideal to mellow as nighttime approaches, but caregiving is stressful, and if the day has been difficult it can be hard to hide its effects. This can cause an aggravated response in someone with dementia, and make it more difficult to go to sleep.
Sleep Apnea and Alzheimer’s/Dementia
Sleep apnea is a potentially serious disorder in which breathing repeatedly stops and starts during sleep. This can be because of relaxing muscles in the throat or a problem with signals from the brain, and researchers have found that a gene associated with Alzheimer’s disease is also prevalent in cases of sleep apnea. The genetic link means sleep apnea is another potential cause of restlessness at night for people with Alzheimer’s or other dementia, as sleep apnea’s side effects include waking throughout the night and subsequent daytime fatigue.
Treatments for sleep apnea can be as simple as taking muscle relaxers, sleeping on one’s side, or losing weight, but in cases involving dementia it’s of course more complicated. Continuous positive airway pressure (CPAP) machines, a mask worn while sleeping at night, are often prescribed for sleep apnea but may not be viable for late-stage dementia sufferers because of nighttime confusion. Special dental appliances and surgery are also options, but bring their own complications. If your loved one with dementia suffers from sleep apnea, consult with a doctor about treatment options.
A study of Alzheimer’s patients and CPAP machines conducted by the University of California, San Diego found that people in the early stages of Alzheimer’s could tolerate sleeping with their masks for about five hours nightly, and also demonstrated mild cognitive improvement.
Sundowning is a term for increasing anxiety, confusion, or aggression at the end of the day, reported in roughly 20 percent of people with Alzheimer’s. The exact reason sundowning occurs is not medically established. Someone with Alzheimer’s may simply be more tired. It’s also possible that the difficulties of caregiving become less tolerable at the end of long days, so caregivers themselves are more sensitive in late evenings to anger and moodiness from a loved one in cognitive decline; sundowning has been reported as a common factor for loved ones deciding to move a person into assisted living communities like nursing homes or memory care. More on sundowning.
Sleep During the Different Stages of Dementia
Sleep quality for someone with Alzheimer’s changes over time. In the disease’s late stages, sleeping more during both day and nighttime is common because day-to-day activities are more difficult and exhausting. In the first few stages, however, difficulty sleeping is common. In fact, fewer hours of deep sleep in people over 60 has been studied as a possible early sign of Alzheimer’s or other dementia. If someone in the earlier stages of dementia is unexpectedly sleepier than normal, it is important to see a doctor. Drowsiness may indicate a problem like infection or adverse reactions to medication.
Some estimates say it’s common for a person with dementia to be awake for 40 percent of their time in bed at night. There have even been reports of people with Alzheimer’s or dementia whose entire sleep cycle shifts, so they’ll sleep throughout the day and be up all night.
Medications for Sleeplessness Associated with Alzheimer’s/Dementia
Experts advise avoiding sleep medications if possible, because the side effects make accidents like falling more likely, and can increase confusion. However, antidepressants, benzodiazepines, sleeping pills, and antipsychotics have been prescribed to combat dramatic changes to sleep cycles.
Another non-pharmaceutical option may be Cannabidiol (CBD) a compound derived from cannabis plants. CBD has demonstrated medicinal effects without the “high” of marijuana, and research shows it can relieve symptoms of dementia and helps maintain circadian rhythms. More on CBD, its legality and benefits.
Careful consideration of the pros and cons of medicating sleeplessness should of course be prioritized by caregivers, and non-medication methods for helping someone sleep better should almost always be tried first.
Non-Medication Tips to Help with Sleep
- Try to have your loved one wake and go to bed around the same time every day, to establish routine and make the process less disruptive.
- Be conscientious about lighting in the evenings, so it doesn’t get too dark inside but dims enough late in the day to indicate the time of day.
- Red or amber nightlights can help someone who wakes up confused realize that it is still nighttime. (Brighter lighting at night could cause someone to believe it’s day time when it’s not.)
- Create a comfortable sleep environment, with particular attention on temperature and lighting.
- Going outside in the mornings and evenings to experience outdoor lighting has been shown to help maintain our internal body clocks.
- Be mindful of caregiver exhaustion. Body language can express frustration even more powerfully than words.
- Avoid stimulants like coffee and alcohol. Watching TV at night has also been shown to excite a person and make sleep more difficult.
- Active days can be essential for sleep. Regular daily exercise is good for the brain and also helps with restlessness. Try to avoid physical exertion in the evenings, however, as this may make a person more hyper.
- The best time for naps is before noon. Afternoon naps can cause someone to feel less sleepy at night.
- Soft music or white noise machines (even just a fan) have been demonstrated to help some people fall more easily into sleep.
- Massage may also help a person fall more easily into sleep.
What Makes Someone a Heavy Sleeper (and How Do You Become One)?
If you’ve ever shared a bedroom with someone, you’re probably aware of the fact that some people can sleep so deeply that you could blast the TV at full volume and they wouldn’t even stir, whereas others require the perfect cocktail of darkness, silence, and temperature to keep them asleep. You may even be both of those people in a single lifetime—or even in a single week. But what exactly makes someone a light sleeper or a heavy sleeper? Turns out, the answer is fairly complicated: Sleep, like most other facets of human life, involves a lot of factors.
“Assuming everyone has a healthy lifestyle, there is individual variation,” says Jocelyn Y. Cheng, MD, assistant professor of neurology with a specialization in sleep medicine at NYU Langone. So even after ruling out differences in lifestyle—diet, activity, substance use—and disorders like sleep apnea, our sleep habits can still vary greatly.
But what is “deep sleep” anyway?
We all go through cycles of deeper and lighter sleep every night, so the difference between a heavy and a light sleeper may be the amount of time a person spends in certain phases of their sleep cycle.
As you may remember from high-school biology, there are four stages of sleep that we cycle through every night, from the lightest (falling asleep) to the deepest, wherein the body repairs and strengthens the muscles, brain, and immune system. After each cycle, we enter REM (rapid eye movement) sleep, which is where dreams happen. The NREM (non-rapid eye movement) stages leading up to REM take about 90 minutes, and each REM period lasts a bit longer than the previous one, usually up to an hour by the final REM stage of the night. REM is technically the lightest kind of sleep—closest to waking.
Like many things, sleep is easier when you’re a kid.
The deepest stages, however, are “collectively known as Slow-Wave Sleep (SWS)” and are common when you’re very young, says Michael Perlis, PhD, director of the Behavioral Sleep Medicine Program at University of Pennsylvania’s Perelman School of Medicine. “The large amounts of SWS in early life likely accounts for the deep sleep that young people experience.”
This may explain, in part, why, when you were little, your parents may have been able to carry you from the couch to your bed without you ever knowing, but as an adult, the slightest jostling from your partner might pull you right out of sleep.
Other factors—including lifestyle—play a part.
“Sex, metabolism, and genetics also likely determine how deeply a person sleeps,” Perlis says. Studies have found that women tend to preserve their slow-wave sleep better than men. However, there is an overall decline in slow wave sleep as we age, but there is more decline in men overall.
Hormones and other brain functions are also part of the sleep/waking cycle, including systems that specifically keep you from waking up. And when you’re awake, sleep-promoting substances accumulate in your brain—essentially getting you more and more ready to go to sleep the longer you stay awake.
Your environment factors into your sleep quality too. While Perlis and Cheng both recommend a quiet, dark, cool environment for sleeping, most of us already know how we sleep best—even when that means lights, music, or the TV on.
“If somebody is already habituated to something, they go to sleep when they’re tired and wake up when they want to, and it doesn’t really interfere with their functioning during the day, it’s truly not going to be much of a problem,” Cheng says. So if you’re used to sleeping with noise or sound in your environment, and it doesn’t seem to be negatively impacting your quality of sleep, there’s probably no harm in it.
This is probably part-idiosyncratic and part-habituation—no one knows exactly why one noise/light environment works better for some people than others, except that you generally sleep best with whatever you’re used to. Perlis adds, however, that “predictable or monotonous noise” can help mask unexpected sounds in the night to help prevent sudden waking for those of us more sensitive to noise. White or pink noise, he says, is generally better for this function than television.
You may just be more (or less) sensitive.
“Part of this may have to do with the individual’s neurobiology—their strength of sensory inhibition during sleep,” Perlis says.
“For reasons we don’t understand, some people just happen to be more sensitive to certain provoking factors. Some people tend to be very sensitive to light, and that’s not uncommon, because light is one of the strongest zeitgebers (environmental clues) for keeping us awake,” Cheng says.
Other atmospheric factors also play a part in shaping a person’s circadian rhythm. But ultimately, people are different: Just like genetics and other inbred factors can hard-wire what makes some of us happy running on six hours of sleep while others can’t function without a full eight, some of us are just naturally more sensitive sleepers. If you’re one of these, that doesn’t mean all hope is lost, however: There are definitely a variety of ways to help yourself sleep better—whether or not you lucked out in the genetic sleep lottery.
Ariana DiValentino is a writer and filmmaker based in Brooklyn. She is very, very worried. You can follow her on Instagram and Twitter.
Can You Stop Being A Light Sleeper?
Some people have the ability to sleep through an earthquake, while others wake at the smallest sound. Being a light sleeper can mean you have a regularly disturbed sleep. It can be frustrating and, at times, mean that you end up lying awake for hours or never feeling refreshed. But is there a science behind why some people are light sleepers? If so, how can they change it? We investigate light sleeping and whether you can stop it.
What is light sleeping?
Your sleep consists of cycles of REM (rapid eye movement) and NREM (none-rapid eye movement) cycles. You spend about 75% of your sleep in an NREM state, which is broken down into different stages of relaxation. Light sleep is categorised as ‘stage 1’. This is the phase at which your body is in between being asleep and awake. Light sleepers tend to remain in this phase for most of their sleep which therefore means they are awakened more easily.
Everyday Health says ‘In general, young people spend more time in the deeper, heavier stages of sleep as they grow and develop. Older people spend less time in deep sleep stages and are more likely to complain of being light sleepers’. However, age isn’t the only factor when it comes to how deeply you sleep. Certain lifestyle factors can disrupt your sleep such as poor diet, medical conditions and a poor sleeping environment.
Read more: How To Reset Your Body Clock
When sleep is disrupted, your body does not have enough time to become relaxed for REM sleep. Sleep expert Phil Torbet says ‘Light sleeping is a function of not getting enough REM sleep. And in many cases, disruption of sleep at night is directly related to tossing and turning which interrupts REM sleep’. Having a sleeping environment that is uncomfortable can cause you to wake up. Before going to sleep, ensure that your room is a nice temperature and there isn’t too much light.
You should also consider whether your mattress is suitable. If you are waking up in the night in pain or feeling restless, you may need to replace your current mattress. It’s important to think about getting a new one if yours sags, has broken springs or doesn’t offer the support you need. Use our bed and mattress guide for more help on finding the perfect mattress for you.
Aside from environmental and lifestyle choices, could there be a scientific reason for light sleeping? Sleep researchers at Harvard Medical School and Massachusetts General Hospital think there is. They have identified that some people’s brains are better at blocking out the ambient sound- the constant background noise that usually goes unnoticed. Discussing the study, Time Magazine say ‘as it continually monitors stimuli from the environment to protect against threats, the brain also actively blockades them to allow body and mind to recharge and rest during sleep’. It is this inability to effectively block the response that wakes us up due to an innate need to be alert to danger.
The research focused on patterns produced by the thalamus- a region deep in the brain responsible for processing visual and auditory stimuli. Neurologist Dr Jeffrey Ellenbogen discovered that the number of pulses generated by the thalamus, known as sleep spindles, varied per person. The participants with a higher number of spindles slept through sounds easier.
Ellenbogen says that ‘more spindles meant they were more likely to be protected from sleep disruption’. If more work is carried out, this could mean a positive change for those with fewer spindles.
Are you a light sleeper who is struggling to stay asleep or do you have any tips? If so, tell us your story in the comments.
I’m a Light Sleeper. This Is How I Finally Found Rest
Then, last year, while living in sublet rooms and hostels in Mexico, I came up with a portable sleep solution that addressed my sensory needs around noise, light, and touch. This, along with my established routine, helps take focus off of the stressors of the day and cues my body to sleep.
Of course, I’ve tried sleeping with earplugs and turning a box fan on high, but neither method blocked sound well enough for my sensitive ears. So now I fall asleep wearing in-ear headphones — I use MiniSo ($25), which are comfortable enough to wear in bed — and listening to a free app called Brain Wave Therapy.
You choose a type of repetitive binaural wave (the app has suggestions for what each frequency is suited for) and a duration. It works better than trying to fall asleep to music. Not only does it block noise, but the sound itself is soothing: just hearing it begins to lull me to sleep.
For my light sensitivity problem, which can also trigger migraines during the day, I use an eye mask from Alaska Bear ($10) that has a nose baffle and two straps. I’ve found two straps help keep the mask secure and better molded to my face.
If light isn’t your problem, maybe you haven’t thought about touch — the feeling, weight, or material of my bedsheets or clothes can keep me awake.
Wearing loose pajamas was irritating because they bunched up when I moved. Now I wear cotton leggings that stay put when I turn or fidget and a cami tank top or a fitted shirt, depending on the weather.