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Sleep 35

Sleep 101

30 min read

Simon Körösi

Reviewed by: Joanna Elmes

Introduction

 

Sleep problems have become increasingly common today. In Sweden, 43% of the population report having sleep issues. But what does it really mean to suffer from sleep problems? What signs should you be aware of? And what can you do about it? We have put together a set of questions and answers to help you easily find answers to your questions. If you want to delve deeper, you can click on "read more" to further educate yourself. If you feel that you need professional help with your sleep, we are here to assist you by booking an appointment with one of our sleep psychologists.

 

What is sleep?

 

Sleep is a natural recurring state of reduced consciousness where one does not react to stimuli.

 

Why do we sleep?

 

Sleep is vital for our well-being - without it, we cannot survive. The exact purpose of sleep is not fully understood, but intensive research is ongoing to comprehend its complete significance in human functioning and well-being. What is currently known is that sleep enables the body to repair itself and process impressions from the day. One can say that sleep is necessary to cleanse the brain.

 

What happens in the body during sleep?

 

Since sleep is responsible for repairing the body, resting, and processing all the experiences from the previous day, all the mechanisms activated during sleep are designed for precisely that. Here are some examples of what happens in the body during sleep:

Heart rate and blood pressure decrease.

 

Body temperature drops

 

Muscles relax

 

Breathing rate slows down

 

Energy consumption decreases

 

Memories are consolidated

 

The immune system strengthens, and growth hormones are released

 

The brain processes impressions

 

Production of stress hormones decreases

 

What does sleep need mean?

 

Sleep need simply refers to the amount of sleep your body requires to obtain the rest and recovery necessary to be ready for the next wakefulness period.

 

What influences sleep needs?

 

Sleep needs can be influenced by many factors, with the two main ones being:

 

The effectiveness of the previous sleep period - the poorer the sleep quality, the greater the sleep need.

 

Activity level during the previous wakefulness period - the more active, the greater the sleep need.

 

What regulates sleep needs?

 

Sleep needs, like sleep itself, are governed by two different systems: the circadian rhythm and the homeostatic process.

 

Circadian Rhythm

 

The Biological Clock and Circadian Rhythm

Have you ever wondered why some people are early birds while others are night owls? The circadian rhythm, also known as the sleep-wake cycle, is an internal biological clock that regulates wakefulness and sleep. The circadian rhythm programs us to be awake and active during the day and sleep at night in cycles of approximately 24 hours. This means we oscillate between wakefulness and drowsiness at specific intervals. The circadian rhythm is not exactly the same for everyone. Some individuals have a later rhythm and prefer staying up late in the evening, while others have an earlier rhythm, going to bed and waking up earlier. 

External factors such as daylight and darkness influence the circadian rhythm. In darkness, the hypothalamus in the brain signals the onset of fatigue, and the pineal gland begins to release melatonin. Melatonin is a hormone that makes us feel sleepy.

 

The circadian rhythm essentially means that a process in the body occurs on a 24-hour cycle. The circadian rhythm related to sleep is influenced by the biological clock, melatonin, and "zeitgebers."

Biological Clock

 

A biological clock is an organism's internal timekeeper. It is the biological clock that regulates the circadian rhythm. In practice, specific proteins interact and communicate with cells throughout the body. Nearly every organ and tissue in our bodies have biological clocks. When referring to the biological clock in the context of sleep, we mean what is called "the master clock" in English, which is a core in the brain that coordinates all the body's biological clocks. This core is called the suprachiasmatic nucleus (SCN), consisting of approximately 20,000 nerve cells and is directly connected to the eyes to quickly adjust its function to light and darkness.

 

Melatonin

 

Melatonin is a hormone released in the body to promote sleep when we are exposed to darkness. As we age, less melatonin is produced. While many refer to melatonin as the "sleep hormone," there are actually several hormones that induce drowsiness and contribute to sleep, including antihistamines, acetylcholine, and GABA.

 

What happens in the body when melatonin is released? When it becomes dark, signals are sent via the optic nerve to brain nuclei that ultimately result in the release of norepinephrine. Norepinephrine, in turn, stimulates all the steps involved in melatonin production. Increased melatonin production signals the biological clock to reset itself.

 

Zeitgebers

 

Zeitgebers (German for "time givers") are the term used for environmental factors that influence the circadian rhythm. The most obvious ones are light/darkness and temperature, but the level of physical activity and our meal patterns also have an impact.

 

Homeostatic Process / "Sleep Pressure"

 

The homeostatic process, also known as sleep pressure, is the signaling we feel from our bodies telling us that we need to sleep. The higher the sleep pressure, the stronger the signals that we need to rest. The longer it has been since you had adequate sleep, the more likely it is that sleep pressure and the homeostatic process increase.

 

Adenosine

 

Adenosine is a small molecule that serves multiple functions in the body. It acts as a building block in DNA and RNA, functions as a neurotransmitter in the central nervous system, and is perhaps best known as a component of ATP, which is the body's primary and most extensive source of cellular energy. What is also known is that adenosine binds to the same receptors as caffeine but with the opposite effect.

 

Ongoing research has shown that adenosine levels increase the longer we stay awake, and higher levels of adenosine correspond to higher sleep pressure.

 

What does sleep pressure mean?

 

Sleep pressure refers to the signaling we feel from our bodies telling us that we need to sleep. The higher the sleep pressure, the stronger the signals that we need to go to bed.

 

What influences sleep pressure?

 

Sleep pressure is influenced by several factors, with the most common ones being:

The time since we last slept - the longer we abstain from sleep, the higher the sleep pressure becomes

 

The amount of adenosine accumulated during a period of wakefulness, which is directly linked to the number of hours we stay awake

 

The quantity and intensity of physical activity during the day (one should not drive a car after participating in Vätternrundan due to the significantly increased risk of falling asleep at the wheel)

What does sleep consist of?

 

Sleep consists of multiple components that together make up the entirety of sleep. These components represent different frequencies and patterns of brain activity, with each pattern and frequency playing an important role in the body's ability to repair and recover. Sleep components are often categorized into three concepts: sleep stages, sleep phases, and sleep cycles.

 

Sleep is composed of periods of varying brain activity that follow a specific pattern. These different levels of activity are referred to as sleep stages, and one complete sequence is called a sleep cycle.

 

Sleep Stages / What are sleep stages?

 

Sleep stages are the different levels of sleep depth that an individual goes through during the night. Sleep stages are characterized by distinct patterns of brain activity and are often divided into 5 parts: wakefulness, N1, N2, N3, and REM.

 

What are the sleep stages?

 

Wakefulness, N1, N2, N3, and REM. N1-N3 are also referred to as NREM, which stands for non-REM. REM stands for rapid eye movement because the eyes move rapidly during this phase of sleep.

 

N1 - The state between wakefulness and sleep. Breathing occurs at a normal rate, and the muscles are not completely relaxed yet. Hypnagogic hallucinations may occur during this stage. Some individuals may hear a clock, see a light, or experience a sensation of falling. The latter can result in the "jerking" sensation (hypnic jerks) that some people experience, which can cause us to wake up again. N1 lasts for about 1-5 minutes and constitutes approximately 5% of total sleep time.

 

N2 - This stage represents light sleep. It is more difficult to wake a person during this stage. In this stage, heart rate and body temperature begin to decrease, and teeth grinding (bruxism) may occur. N2 is believed to be the stage that filters out stimuli such as loud noises and also stores information in long-term memory. In the first sleep cycle, N2 lasts for about 25 minutes and gradually becomes longer with each subsequent sleep cycle. N2 accounts for approximately 45% of total sleep time.

 

N3 - N3 is commonly known as deep sleep. It is characterized by being difficult to awaken from and having the slowest brain activity. If awakened during this stage, the first 30-60 minutes may show poorer mental capacity and performance. It is during this stage that the body repairs itself, regenerates tissues, strengthens bone and muscle mass, and enhances the immune system. Typically, there is a higher amount of deep sleep in the first few hours of the night compared to the later hours. This pattern ensures that the body receives the necessary recovery even if sleep is disrupted towards the end. As we age, we tend to spend less time in N3 and more in N2. It is during this stage that sleepwalking, sleep talking, night terrors, and bedwetting can occur. N3 accounts for approximately 25% of total sleep time.

 

REM - REM stands for rapid eye movement, and it is the stage of sleep where the eyes move rapidly. REM sleep is most associated with vivid dreaming and is not considered a stage of rest for the body. This is because brain activity during REM sleep resembles that of being fully awake. Skeletal muscles are temporarily paralyzed during this stage, except for the eyes (hence the name) and the diaphragm, which controls breathing. However, breathing during REM sleep is irregular. Initially, REM sleep lasts for about 10 minutes and occurs approximately 90 minutes after falling asleep. Throughout the night, REM sleep gradually increases in duration with each sleep cycle, reaching approximately one hour before waking up. In addition to dreaming, REM sleep is also when nocturnal erections occur. REM sleep accounts for about 25% of total sleep time.

 

Sleep Cycles / What is a sleep cycle?

 

A sleep cycle is a sequence of sleep phases (different sleep stages) that follow a specific pattern. Each night, you go through approximately 4-6 sleep cycles, lasting about 90 minutes each. Individual variation exists, depending on factors such as age and the duration of sleep from the previous night. The length of a cycle can vary by almost an hour. The order of a sleep cycle is as follows: N1->N2->N3->N2->REM->N1, and then it begins again.

 

What are the physiological explanations for sleep problems?

Desynchronized circadian process leading to delays or early phases.

 

Desynchronized secretion of melatonin (too early or too late).

 

Dysfunction in the homeostatic process.

 

Maladaptive behaviors that reduce the homeostatic process.

 

Downregulated GABAergic activity or overactivity of orexin.

 

Overactivity in the hypothalamus, hippocampus, amygdala, and prefrontal cortex.

 

How much sleep do you need?

 

Most adults need 7-9 hours of sleep per night. Some may require more, while others may need less. Children and teenagers have greater sleep needs during their development, which decrease with age.

 

How do I know if I'm getting enough sleep? / Am I sleeping too little?

 

If you have the energy and vitality to handle the day after a night's sleep and feel refreshed, you can assume that you have obtained sufficient sleep. However, if you feel very tired during the first few hours of the morning or struggle to perform tasks throughout the day due to fatigue or lack of energy, there is a possibility that you are not getting enough sleep.

 

Can you sleep too much?

 

Sleeping too much is not common in cases of sleep problems, but it can occur. Sleeping more hours than the average of 7-9 hours is referred to as hypersomnia. In certain conditions such as chronic fatigue syndrome, there may be periods of excessive sleep. This is transient and occurs as a result of the body's need to recover from a prolonged period of insufficient rest. Sleeping more than necessary can be harmful to the body. Common consequences include headaches, fatigue, weight gain, and impaired fertility.

 

What does sleep problem/sleep disorder mean?

 

Sleep problems refer to having disrupted sleep and not getting the necessary amount of sleep. Sleep problems can be categorized into acute/short-term sleep problems and chronic/long-term sleep problems. Acute sleep disorders involve experiencing sleep problems for a few days up to a few weeks. Chronic sleep disorders involve experiencing problems for at least four weeks, at least three days per week, despite having the conditions for good sleep.

 

Why do I wake up in the middle of the night?

 

It is not uncommon to wake up in the middle of the night. It happens to all of us multiple times throughout the night, and as long as we fall back asleep within about 30 seconds, we don't remember it the next day. We only remember the instances where we have difficulty falling back asleep, and therefore, we store the event in our memory until the following day. If you experience frequent awakenings during the night and feel tired during the day, it may be a good idea to seek help for your sleep issues.

 

What causes sleep problems? / What are the most common causes of sleep problems?

 

Sleep problems are common in relation to acute or disruptive life events such as fleeing, divorce, or losing one's job. Even problems that we need to solve and have difficulty letting go of due to their magnitude or perceived time pressure often cause sleep problems. Sleep is directly affected by worry and stress in our bodies. Sometimes the stress comes from external factors, sometimes it arises internally. Sometimes it is caused by something we have consumed, and sometimes it is due to something we have not consumed enough of.

 

The most common causes of disturbed sleep are insomnia and sleep apnea, but there are many common causes of sleep problems:

 

Stress

 

Anxiety

 

Irregular sleep schedules

 

Changes in life circumstances

 

Shift work

 

Depression

 

Underlying medical conditions

 

Alcohol, caffeine, and nicotine

 

Snoring

 

Poor sleep environment

What is insomnia?

 

Insomnia is the medical term for sleeplessness. Insomnia involves recurring sleep problems that persist over a longer period (more than one month) and negatively impact well-being and daytime functioning. Insomnia is characterized by the experience of not sleeping well enough or long enough to feel rested and refreshed. This results in impaired daytime function and diminished quality of life.

 

How do I know if I have sleep problems?

 

There are several signs that may indicate you have sleep problems.

You have difficulty falling asleep at night (takes over 30 minutes).

 

You experience interrupted sleep (three or more awakenings or a single awakening lasting over 45 minutes during the night).

 

You have sleep problems several times a week.

 

Your sleep problems affect your daily life and social interactions.

 

Your sleep problems affect your daily life and social interactions.

 

You feel tired, and you find that sleep doesn't provide enough restoration.

 

What consequences can sleep problem have?

 

Experiencing sleep problems over a prolonged period can affect both your mental and physical health. Long-term sleep problems can lead to:

 

Fatigue and lack of energy.

 

Emotional imbalance.

 

Difficulty concentrating.

 

Memory difficulties.

 

Weakened immune system.

 

Increased risk of traffic accidents.

 

Increased risk of various conditions such as diabetes, depression, cardiovascular disease, and Alzheimer's.

 

What can I do about my sleep problems?

 

To understand what you can do about your sleep issues, it's important to determine the underlying causes in the first place. Once you understand the possible causes, actions can be divided into two subcategories: self-help methods to improve sleep and seeking professional assistance.

 

Sleep tips

 

There are various advice and routines you can follow and implement to address your sleep problems on your own. Here are some sleep tips that can help you sleep better:

 

Establish consistent evening and bedtime routines. Humans are creatures of habit, and sleep is no exception. By having a clear and consistent bedtime routine each night, you can help your body establish a better sleep pattern throughout the day and, as a result, facilitate improved sleep.

 

Wind down before bed. Give yourself at least 60 minutes for relaxation before going to sleep. Consider what helps you feel calm, whether it's a breathing exercise, mindfulness, reading a book, or listening to soothing music.

 

Maintain regular sleep times by going to bed around the same time and waking up at the same time every day.

 

Try to wake up at a similar time each day, regardless of the time you fell asleep during the night (including weekends).

 

Avoid sleeping in if possible. If you do choose to sleep in, make sure not to wake up more than 2 hours later than your usual time.

 

Professional help

 

If you feel that your own efforts to address your sleep problems have not been sufficient, you should consider seeking professional help.

There are different types of professional help available, and the specific assistance suitable for you depends on the type and severity of your sleep problems. Sleep problems can be treated using the following strategies:

 

CBT (cognitive behavioral therapy)

 

Sleep medication

 

Relaxation techniques

 

Sleep hygiene advice (see the sleep tips section)

CBT and sleep therapy

 

CBT (cognitive behavioral therapy) is the recommended treatment for sleep problems by the Swedish National Board of Health and Welfare. CBT involves familiarizing yourself with and confronting your thoughts, feelings, and behaviors. The goal of CBT is to reflect on your situation, what you do, how you do it, and why, and then use that insight to create new thought and behavior patterns that promote better sleep.

 

Sleep medication

 

For many, sleep medication is a quick and easy way to try to alleviate sleep problems. The prescription of these medications has increased significantly in recent years, and over a million Swedes currently use sleep medication to some extent. While there are positive effects of medication, there are also downsides to consider before starting.

 

- Sleep medication can lead to psychological and physical dependence.

- Sleep medication can further complicate sleep without medication.

- Sleep medication can lose its effectiveness with long-term use.

- Sleep medication should never be used as a permanent solution for sleep problems!

 

Melatonin and melatonin tablets

 

Melatonin is the body's most important sleep hormone. Its release is activated when it's dark and inhibited when it's light. Difficulties in producing melatonin can negatively affect sleep. Melatonin is available as both an over-the-counter and prescription medication.

 

Advantages of melatonin tablets:

- Non-addictive

- Naturally occurring hormone

- Can help with sleep disturbances

 

Disadvantages of melatonin tablets:

- Often cause side effects such as headaches and drowsiness

- Occasionally cause side effects such as dizziness, anxiety, weight gain

- In rare cases, can cause side effects such as mood changes, impaired memory, and visual impairment

- Long-term risks are not yet fully understood.

- Relaxation techniques

 

A significant cause of sleep difficulties can be the inability to unwind, both during the day and at night. With relaxation techniques, you receive support and guidance to help you achieve a sense of calm in your body and activate this calmness whenever you wish.

Sleep medication can lead to psychological and physical dependence.

 

Sleep medication can further complicate sleep without medication.

 

Sleep medication can lose its effectiveness with long-term regular use.

 

Sleep medication should never be used as a permanent solution for sleep problems!

 

Melatonin and melatonin tablets

 

Melatonin is the body's most important sleep hormone. Its release is activated when it's dark and inhibited when it's light. Difficulties in producing melatonin can negatively affect sleep. Melatonin is available as both an over-the-counter and prescription medication.

 

Advantages of melatonin tablets:

 

Non-addictive

 

Naturally occurring hormone

 

Can help with sleep disturbances

 

Disadvantages of melatonin tablets:

 

Often cause side effects such as headaches and drowsiness

 

Occasionally cause side effects such as dizziness, anxiety, and weight gain

 

In rare cases, can cause side effects such as mood changes, impaired memory, and visual impairment

 

Long-term risks are not yet fully understood.

 

Relaxation techniques

 

A significant cause of sleep difficulties can be the inability to unwind, both during the day and at night. With relaxation techniques, you receive support and guidance to help you achieve a sense of calm in your body and activate this calmness whenever you wish.

 

When should I seek medical care?

 

If you have experienced sleep problems for at least three nights per week for a month and any of the following apply:

 

Your sleep does not provide sufficient recovery.

- You are unable to improve your sleep on your own.

- The sleep problem causes distress and daytime symptoms that affect your daily life.

 

Why do we dream?

 

Over the years, researchers have tried to understand why we dream. What we know is that we have approximately 4-6 dreams per night, with the most vivid dreams occurring during REM sleep when we are most physiologically active. During dream sleep, emotional memories and impressions from the day are processed. The content of dreams can be both positive and negative. When we get enough sleep in the morning, we often wake up in close connection to a dream and find it easier to remember parts of the dream.

 

What is parasomnia?

 

Parasomnia refers to unusual/abnormal behavior during sleep.

Examples of parasomnias:

 

- Night terrors

- Sleep talking

- Sleepwalking

- Teeth grinding

 

Why do we talk in our sleep?

 

The phenomenon of talking in our sleep is still not well understood. It is believed to have a genetic component, although the exact link is not fully established. Additionally, individuals with mental health conditions such as PTSD are more likely to exhibit increased tendencies to talk in their sleep, but most sleep talkers do not suffer from mental illness.

 

Up to 66% of people are believed to talk in their sleep. However, it often goes unnoticed unless a partner or family member observes it. The actual prevalence may be significantly higher, and individuals who regularly talk in their sleep sometimes need to be recorded for several consecutive nights to capture the behavior. Sleep talking is more common in children than adults, and the occurrence is equally prevalent among men and women.


Unlike other parasomnias that often occur in a specific stage of the sleep cycle, such as a particular sleep stage, sleep talking can happen in both REM sleep (dream sleep) and non-REM sleep (non-dream sleep). Sleep talking is not the same as a person speaking while acting out their dreams, which is known as RBD or REM sleep behavior disorder. When sleep talking occurs, it can resemble normal speech or be unintelligible. The content of sleep talking often lacks direct connections to the individual's life, and there are some indications that it may occasionally be related to dreams, although the source of the content is not yet fully understood. It is very rare for someone to remember talking in their sleep upon waking up. Sleep talking typically occurs in short sequences, and sometimes the sleep talker can interact with an awake observer. The exact reasons why some people talk in their sleep are not established, but stress, fever, sleep deprivation, and depression can increase the risk.

 

Is sleep talking dangerous?

 

No, sleep talking is not dangerous.

 

Can sleep talking cause problems?

 

In the vast majority of cases, sleep talking is completely harmless. It is uncommon for the sleep talker to be disturbed by it, and it occurs infrequently enough for it not to become a problem for the partner or family members.

 

However, there are a few situations where sleep talking can cause problems:

 

- If the sleep talking disrupts the sleep of a roommate or bed partner to the extent that it creates sleep difficulties and daytime tiredness for them.


- If the content of the sleep talking causes embarrassment or shame, leading to relationship problems between you and your roommate/bed partner.

 

- If sleep talking occurs concurrently with other parasomnias, such as sleepwalking, it may be associated with a more extensive sleep disorder.

How can I stop sleep talking?

 

Since the exact cause of sleep talking is not fully understood, there is limited knowledge about effective methods to stop the behavior. In most cases, there is little point in attempting to treat it as it occurs infrequently and has minimal negative consequences. However, if you still wish to address it, focusing on good sleep hygiene is often a good first step. Most parasomnias are considered abnormal states that blur the boundaries between sleep and wakefulness. These conditions are believed to become more common when normal sleep patterns and cycles are disrupted. For this reason, the initial recommendation is to promote consistent and uninterrupted sleep.

 

What is sleep hygiene?

 

Sleep hygiene refers to both internal and external factors that can affect sleep. External factors refer to the sleeping environment, while internal factors refer to a person's habits that can influence sleep.

 

How can you influence your sleep hygiene?

 

When we talk about influencing sleep hygiene, we mean making changes to routines that can impact sleep and the sleep environment.

 

Examples of how to influence your sleep environment:

 

- Ensure darkness in the place where you sleep

- Ensure a quiet environment

- Ensure a cool temperature

- Keep screens out of the bedroom

 

Examples of how to influence your sleep routines:

 

- Go to bed at the same time every night.

- Avoid engaging in stimulating activities such as reading emails before bed.

- Avoid screens one hour before bedtime.

- Avoid consuming caffeine late in the afternoon/evening.

- Get adequate daylight exposure and engage in physical activity every day.

- Establish a relaxing pre-sleep routine to unwind before bedtime.

 

Why do people sleepwalk?

 

The exact explanation for sleepwalking is unknown. However, several factors can increase the risk of sleepwalking:

 

- Heredity (possibly the strongest factor)

- Sleep deprivation

- Fragmented or poor-quality sleep (more common in conditions like sleep apnea and restless legs syndrome)

- High fever (infection)

- Medications (especially sleep medications)

- Stress

- Anxiety

- Not emptying the bladder before going to bed

- Change in sleeping environment

- Being woken up by someone else in the middle of the night

- Migraines

- Head injuries

 

What is sleep hygiene?

 

Sleep hygiene refers to both internal and external factors that can affect sleep. External factors refer to the sleeping environment, while internal factors refer to a person's habits that can influence sleep.

 

How can you influence your sleep hygiene?

 

When we talk about influencing sleep hygiene, we mean making changes to routines that can impact sleep and the sleep environment.

 

- Examples of how to influence your sleep environment:

- Ensure darkness in the place where you sleep.

- Ensure a quiet environment.

- Ensure a cool temperature.

- Keep screens out of the bedroom.

 

Examples of how to influence your sleep routines:

 

- Go to bed at the same time every night.

- Avoid engaging in stimulating activities such as reading emails before bed.

- Avoid screens one hour before bedtime.

- Avoid consuming caffeine late in the afternoon/evening.

- Get adequate daylight exposure and engage in physical activity every day.

- Establish a relaxing pre-sleep routine to unwind before bedtime.

 

What is a power nap?

 

There is no scientific definition of a power nap, but most people consider it a short period of sleep during the day with the purpose of increasing alertness for the remaining awake period. This distinguishes it from nighttime sleep. The length of a power nap can vary from a few minutes up to 2 hours.

 

Is taking a power nap beneficial?

 

Extensive research has been conducted in recent years to understand the effects of power naps on health and well-being. Among all sleep-related conditions causing daytime sleepiness, only narcolepsy has shown positive effects from taking power naps.

 

Is taking a power nap dangerous?

 

A meta-study from 2016 indicated associations between power naps longer than one hour and increased risk of cardiovascular diseases, diabetes, metabolic syndrome, and mortality. No risks were observed for power naps of up to 40 minutes, but there was a clear threshold for health risks when the duration of power naps exceeded a certain limit.