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What is it

Sleep latency is the term given to describe how long it takes to fall asleep. Sleep latency can be highly variable due to behaviors prior to bedtime, such as alcohol, medications, exercise, diet, and blue light exposure, among others. However, tracking sleep latency can provide additional data that can reflect changes in health, behavior, and their interaction.

How is it measured

Sleep latency is measured in minutes from the time an individual attempts to fall asleep to the time when the individual enters sleep. While this can seem rather easy to qualitatively assess for an individual, tracking changes in physiological metrics through photoplethysmography (PPG) and accelerometry provides improved insight as individuals may have difficulty reporting the time of initial sleep onset. By tracking metrics such as heart rate, heart rate variability, respiration rate, and limb movements, a good understanding of bed time and onset of sleep can be made.

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Correlations to health conditions

The connection between sleep onset latency and clinical outcomes is less clear than that of total sleep time and deep sleep duration, however, there appears to be correlations between them. It is important to note that directionality and magnitude of latency may or may not have clinical relevance based on the situation that an individual is in. For example, long sleep latencies can be indicative of disorders, particularly related to stress or insomnia; however, shortening sleep latency may not reflect positive changes, as sleep latency is decreased by high amounts of sleep debt and may not reflect an overall positive change. Further, substances such as alcohol may reduce sleep latency but may lead to lesser quality of sleep.

Many of the correlations between latency and health are drawn in anxiety and depression. These psychological disorders are fairly common and are known to affect sleep and sleep latency. However, sleep latency is associated with total sleep duration reduction, which has a feed-forward effect on sleep, where less sleep causes more anxiety and depression. Thus, it can be important to monitor sleep latency changes to catch trends before they become problematic.

Normal or acceptable ranges

The National Sleep Foundation acknowledges up to 30 minutes of sleep latency, regardless of age, as appropriate. Sleep latency of 31-45 minutes is listed as ‘uncertain’, which could be due to individual trends. It stands to reason that very short sleep latency (<5 minutes) could indicate problems with fatigue and sleep deprivation, however, the research on normative values in this range are unclear.

Interpreting trends

Although the clinical recommendations remain unclear, tracking sleep latency could be good for most individuals. This metric, inversely associated with total sleep duration, could provide insight into behavioral changes and how they affect sleep architecture. Should sleep latency trend negatively for an individual, behavioral interventions could be suggested to correct sleep latency, and potentially increase total sleep duration. 

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What is it

Snoring is characterized by partial obstruction of airways that results in noise while breathing. While snoring is a fairly common occurrence, it has the potential to affect sleep quality and physiological parameters, while some snoring can be benign. In addition, snoring can be disruptive to other individuals’ sleep if present in the same room, and is a fairly common stressor for families and partnerships.

How it is measured

Snoring is most often measured by microphone recording during sleep. Biostrap uses the microphone in the individual’s phone, placed near their bed during sleep, which can detect snoring patterns throughout the night. This allows measurement of frequency and intensity of snoring that is otherwise difficult to quantify without a sleep study. 

Biostrap reports snoring level severity as: none, mild, moderate or severe

Correlation with health conditions

Snoring itself can wake up both the individual and others present during sleep, which can affect sleep quality and duration, leading to increased fatigue. However, more importantly, snoring can be associated with obstructive sleep apnea. Obstructive sleep apnea is when airways are obstructed enough to restrict airflow. In typical sleep apnea, airflow is restricted for 10+ seconds for an average of 5 times per hour. This can lead to impaired oxygen transportation and have downstream physiological effects.

Many times, sleep apnea requires intervention in order to improve health outcomes associated with the disorder. While snoring can occur in the absence of sleep apnea, snoring intensity (measured in decibels) is positively correlated with obstructive sleep apnea intensity, and therefore warrants monitoring of snoring frequency and intensity, along with other physiological metrics to screen for sleep apnea.

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Normal or acceptable range

It is estimated that ~49% of people experience occasional snoring, while 10-36% of people snore regularly. Currently, there are no recommended ranges or normative values for snoring, but generally less is better. Simple interventions, such as postural changes, breathing devices, and room conditions, can lead to decreased snoring, potentially increasing sleep quality. 

Interpreting Trends

Monitoring snoring over time may illustrate if/when snoring begins to affect physiology. Should snoring coincide with decreased SpO2, increased heart rate, awakenings, or self-reported fatigue, it is likely that snoring is affecting the quality of sleep, and may warrant intervention. Any changes in behaviors aimed at reducing snoring (postural changes, breathing devices, or room conditions) can be quantified using Biostrap’s sleep analysis, measuring snoring, sleep stages, awakenings, heart rate, SpO2, and more. 

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What is it?

Sleep duration is simply the amount of time that an individual is asleep per night. Regardless of sleep stage, this measure has been shown to be an important factor to quantify, as it directly impacts physiological and psychological parameters in both the short and long term, impacting health, performance, and longevity.

What does it measure?

Sleep duration is the total sum of time spent asleep, regardless of sleep stage, excluding time spent awake while in bed. Using combinations of heart rate, heart rate variability, breathing, motion, and pulse waveform data, approximating sleep versus awake time is possible.

Biostrap uses inputs from all of the listed measurements to estimate light sleep, deep sleep, and time spent awake; therefore, the reflected sleep duration is the sum of light and deep sleep.

Correlation with health conditions

Adequate amounts of sleep have been tied to numerous health outcomes and remains a widely-studied topic. While sleep quality has been the focus of more recent research, the total sleep duration still remains a commonly reported metric and highly correlated with health outcomes.

Sleep is highly important to regulating biological processes, allowing for adaptation, recovery, and preparation. Many repair processes occur during sleep, with surges in growth hormones and reduction in stress hormones. Physiologically, increased sleep duration has been shown to reduce stress, improve cardiovascular markers (e.g. heart rate, heart rate variability, and arterial stiffness), reduce weight gain, improve immune function, and lower risk of all cause mortality and varying diseases. As such, sleep appears to improve physiological pathways robustly.

In addition to physiological effects, there are many cognitive benefits of increased sleep, including improved memory, problem solving, and reaction speed.

Normal or acceptable range

The American Academy of Sleep Medicine recommends at least 7 hours of sleep per night for adults aged 18-60 years, with the National Sleep Foundation recommending supplementing this recommendation with 7-9 hours of sleep per night for adults aged 65 years and older.

Biostrap records users’ sleep each night, and from this data, we can gather average values of distinct populations.

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Interpreting Trends

Considering the broad health implications associated with sleep duration, tracking sleep duration over time is recommended so an individual may notice trends in their behavior. This metric can be seen as a health behavior, and thus influences passively obtained physiology metrics. However, sleep duration can be monitored to see if other lifestyle factors or stressors are decreasing time asleep, which may be hard to notice in some individuals without measurements. Including sleep duration into longitudinal metrics can either explain or rule out other physiological trends, and therefore is included in Biostrap biometrics, allowing users and remote monitors to have a broader view of individual health.

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What is deep sleep

Sleep can be broken down into different ‘stages’ of sleep. Most commonly, sleep is divided into rapid eye movement sleep (REM) and non-REM (NREM) sleep. NREM sleep accounts for the majority of sleep (75-80% of total sleep duration), while REM sleep makes up the rest. Within NREM sleep, there are four stages; the first stage is light sleep and is mostly the transitory onset of sleep; the second stage is also considered light sleep, but makes up a longer duration than stage 1.

The third and fourth stages are considered ‘deep sleep’ and are characterized by slow brain waves. Deep sleep makes up roughly 13-23% of nightly sleep. It is during these stages that sleep is restorative and leads to many adaptive physiological outcomes that help the body adapt and repair. As such, deep sleep has been shown to be more important than total sleep time in affecting physiological outcomes.

How it is measured

Deep sleep is often identified by slow waveforms on an electroencephalogram (EEG), which measures brain wave activity. As an alternative, deep sleep has been shown to have decreased movement and altered vital signs, particularly: lower heart rate, higher heart rate variability, lower blood pressure, lower temperature, and decreased sympathetic activity, among others.

By measuring these changes using wearable technologies (accelerometers and photoplethysmography [PPG]), a close approximation of sleep stage can be made. Using this technology allows for passive measurement with much less equipment than a traditional EEG or polysomnogram.

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Correlation with health conditions

Much like with total sleep time, the restorative benefits of deep sleep have robust physiological effects across many organ systems. However, deep sleep appears to be a better indicator of the quality of sleep, compared to the total duration of sleep.

Deep sleep has been shown to affect growth hormone production, glucose metabolism, synaptic processes (e.g. learning/memory formation), and immune function changes. Sleep restriction, affecting the duration of deep sleep, has been linked to many negative health outcomes, including cardiovascular disease, diabetes, neurodegenerative diseases, poor cognitive function, and many more conditions. As such, it is important to get adequate amounts of sleep that is of good quality, permitting deep sleep.

Normal or acceptable range

Currently, there are not widely accepted values specific to deep sleep. There appears to be an age-related decline in the duration of deep sleep, with minimal change in other sleep stages, in absolute terms. Of each sleep session, most individuals have 13-23% of their duration in deep sleep. The recommended amount of deep sleep has not fully been evaluated, but many experts believe that it is better to have more than less, although high amounts of deep sleep may indicate short term deficiencies.

Interpreting trends

While it is relatively easy to approximate total sleep time by tracking sleep and wake times, deep sleep is much harder to quantify. Use of EEG devices provide a strong understanding of sleep stages and progressions but are less obtainable for an individual on a regular basis. However, using accelerometers and PPG wearables, such as Biostrap, light and deep sleep can be approximated on a nightly basis, and easily tracked over time.

As with total sleep duration, tracking deep sleep can provide insight into its contribution to changes in physiological variables, cognitive and/or athletic performance, mood, fatigue, and other health-related outcomes. As a variable that is more challenging to quantify, monitoring deep sleep over time can also provide insight into lifestyle changes and how they affect deep sleep. For example, tracking how a medication affects deep sleep may provide insight into its efficacy or side effects.

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When it comes to getting enough sleep, we have a habit of trying to cut corners. Seven or eight hours of sleep may sound ideal, but rarely do we seem to have the time.

According to the National Sleep Foundation, older adults should sleep between 7-9 hours each night. This recommendation only increases amongst teenagers, preschoolers, and toddlers. Yet despite this advice, 45% of Americans say that poor or insufficient sleep has affected their daily lives at least once in the past week.

Getting a good night’s sleep isn’t easy, but it’s essential. Let’s pull down the sheets to learn more about sleep, why 6 hours of sleep simply isn’t enough for most people, and what we can do to ensure we’re getting the hours of shuteye we need.

The Basics of Sleep

There are four primary stages of sleep to be aware of, and we collectively refer to these stages as the sleep cycle.

The first stage is the lightest stage of sleep when you’re just dozing off. During this stage of drowsy sleep is when you may experience slight twitching such as Hypnic jerks, and you can also easily be woken. Your muscles will relax and your brain will begin to slow down as your body prepares for a more restful, deep sleep.

The second stage of sleep is when body temperature will begin to drop and heart rate and breathing rate both slightly decrease. You can’t be woken as easily during this stage of sleep, and your brain will continue to slow down as bursts of brain activity called sleep spindles occur. Research suggests sleep spindles protect the brain from awakening during sleep.

The third stage of sleep is known as slow-wave sleep. This is the most restorative stage of sleep and is marked by delta brain waves. Some of the most essential bodily processes occur during this stage including hormonal balancing, human growth hormone release, brain detoxification and memory consolidation.

The fourth and final stage of sleep is known as rapid eye movement, or REM, sleep, and this is where dreaming takes place. While your muscles will be “paralyzed”, brain waves will become more active, behaving nearly as if you were awake. Getting an adequate amount of REM sleep is very important for cognitive functions as well as memory. 

Generally speaking, your body will spend more time in deep sleep during the first half of the night and more in REM during the second half.

Ensuring you reach each of these four stages of the sleep cycle is extremely important. One sleep cycle, which will include all four stages of sleep, will often last approximately 100-120 minutes, and you’ll transition through four or five full cycles per night.

For Most Of Us, 6 Hours of Sleep Isn’t Enough

We hate to burst your bubble, but six hours of sleep just isn’t enough for the average individual. While some people do well on only six hours of sleep, most of us would benefit from an extra hour or two of additional rest. Below we’ve included the nine primary sleep groups identified by the Centers for Disease Control and Prevention, along with their corresponding sleep recommendations.

Newborns
​Newborns should receive between 14 and 17 hours of sleep, though 11 to 13 hours is acceptable as well. Ultimately, newborns shouldn’t sleep less than 11 hours per day.

Infants
Infants should sleep between 12 and 16 hours, including naps.

Toddlers
Toddlers should sleep between 11 and 14 hours each day, including naps. Toddlers shouldn’t sleep less than 9 hours per day.

Preschoolers
Preschoolers should sleep between 10 and 13 hours per day, including naps.

Children (6-12 years of age)
Children should get 9 to 12 hours of sleep.

Teens (13-18 years of age)
Teens should get 8 to 10 hours of sleep per day.

Adults (18-60 years of age)
Young adults should get 7 to 9 hours of sleep per day.

Older Adults (61-64 years of age)
Older should get 7 to 9 hours of sleep per day.

Seniors (65 years of age and older)
Seniors should get at least 7 to 8 hours of sleep each night.

Is 6 Hours of Sleep Enough for You?

While 6 hours of sleep isn’t enough for most of us, there are signs you can watch for to determine if 6 hours of sleep is enough for you. For instance, yawning, fatigue, brain fog, and irritability are telltale signs that you’re simply not getting enough sleep.

Other symptoms of tiredness or sleep loss include a lack of motivation, clumsiness, and increased appetite. If you’re sleeping for six hours or less per night while experiencing these symptoms, you’ll need to increase the amount of sleep you’re getting to reflect nightly recommendations for your age, or you’ll need to find ways to improve upon your quality of sleep.

Did you know that Biostrap offers an advanced sleep tracking and analysis feature? In addition to the basic sleep offerings, the Biostrap Sleep Lab provides more frequent biometric recordings (up to every two minutes), plus after a 15-day baseline, you can get personalized sleep time and wake-up time recommendations to help optimize your circadian rhythm and achieve improved sleep quality and recovery. 

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Why Aren’t You Getting Enough Sleep?

Poor sleep or a lack of sleep can often be attributed to a number of factors. From taking sleep for granted to consuming caffeine before bed, sleep problems are widespread. Below you’ll find the common reasons people don’t get enough sleep.

Stimulants

Stimulants such as caffeine, alcohol, and even sleeping pills can interfere with your ability to fall asleep and stay asleep. While substances like alcohol may evoke the feeling of sleepiness, in reality, your sleep will be very restless. Sleeping medications, on the other hand, may be okay to use occasionally, but these become less impactful over time, and you may become dependent on them to fall asleep.

Shift Work

Those who work changing shifts have a more difficult time establishing a consistent sleep-wake pattern. While some adjust to these changes better than others, shift work can influence your circadian rhythm and drastically reduce the amount of sleep you should be getting each night.

Eating & Drinking Late

Eating late may impact the quality of your sleep. Going to bed on a full stomach will not only keep your body busy digesting what you just ate, instead of focusing on sleeping, but as elevated blood sugar levels trigger an insulin response, it can also cause a spike in cortisol which will keep you from transitioning into the sleep stages mentioned above.

Not to mention, certain unhealthy food choices may even cause heartburn, chest discomfort or bloating that may keep you up at night.

As a result, it’s best to avoid any late night snacks before bedtime. If you’re hungry, eat something small, such as a teaspoon of nut butter, and drink a glass of water or a cup of tea. 

Stress

Stress may keep us up at night and disrupt our sleep schedule. Elevated stress levels may keep your fight-or-flight, or sympathetic nervous system, activated, blocking your chance to tap into the parasympathetic, rest-and-digest, nervous system and get a restful sleep. Give yourself a chance to relax and unwind before bed — meditate, journal or do some breathwork — to help your body wind down. If stress is still stopping you from getting quality sleep, speak with your doctor to find techniques for coping with stress.

Sleep Disorders

​Sleep disorders are one of the most common reasons we suffer from sleep deprivation. Sleep apnea, night terrors, insomnia, and more can influence our sleep habits for days or even years at a time. If you suffer from a chronic sleep disorder that stops you from getting a good night’s sleep, consider talking to your doctor to determine what you can do to get back to bed.

Healthy Habits to Develop

Our body’s circadian rhythm is always telling us when it’s time to sleep and when it’s time to wake up. When this internal rhythm is disrupted, however, we’re left with a myriad of negative consequences leading to poor sleep. With this in mind, here are some tips on how to improve your sleep patterns so that falling asleep becomes a breeze.

Follow a Sleep Schedule

It may seem like a no-brainer, but your body prefers a sleep schedule that allows you to fall asleep and wake at the same time each day. This can also reduce your risk of heart disease, which sleep deprivation can increase your risk of developing.

Watch What You Eat

Avoid heavy meals close to bedtime and keep snacking to the minimum. Drinking water or tea before bed is healthy, but too much fluid can result in frequent bathroom trips that negatively impact your sleep duration.

Avoid Bedtime Distractions

Bedtime distractions such as digital screens, bright lights, and loud music can stop you from getting a good night’s sleep. Consider turning off your phone, dimming the lights, and reading a book before bed to allow your body and mind to wind down. A healthy bedtime routine that’s free of distractions will put your head in the right place before it hits the pillow.

Sleep Medicine

Though sleep medicine isn’t recommended for everyone, certain individuals may benefit from sleep medications that aid in falling asleep. If you find yourself suffering from a lack of sleep on a consistent basis, talk to your doctor to determine if sleep medicine is the right avenue for you.

So, Is Six Hours of Sleep Enough?

At the end of the day, six hours of sleep isn’t really enough for the average person. While we all know someone that functions well on less sleep, the side effects that come with a lack of sleep such as weight gain and compromised cognitive performance are reason enough to ensure you’re getting your recommended amount of sleep. While getting the sleep your body craves can be difficult, every hour of sleep you get makes an impact on your overall health.

Consider tracking your sleep with the most advanced digital health solution that’s available right now. Gain valuable insights into your sleep quality and start introducing a data-driven approach to understanding how your lifestyle choices are making an impact on your sleep and recovery.