By Dr. Kimberly Gilmore
Sleep is essential for optimal health and is a natural, periodic state of rest. Sufficient sleep allows the body to properly repair and rejuvenate, facilitating the body to maintain physical and mental health. A recent panel of experts determined that a minimum of seven hours of sleep is recommended for all healthy adults (Watson et al., 2015). Research studies support the need for adequate sleep to maintain health, including improved mood, cognitive function, decreased pain, reduced risk of injury, and healthy weight management (Pigeon, Bishop, & Marcus, 2014).
Sleep is organized into two primary types, non-rapid eye-movement (NREM) and rapid eye-movement (REM). About 75% of sleep in a normal adult is spent in NREM and about 25% is spent in REM. Each stage of sleep is characterized by various attributes such as brain wave patterns, eye movement, muscle tone, and other physiological changes. NREM sleep, which is referred to as deep sleep, has four stages that provide progressively deeper levels of sleep. During NREM sleep, the body repairs and rejuvenates, performing many necessary functions including building bones, repairing tissues, and strengthening the immune system. REM sleep is characterized by vivid dreaming, muscle relaxation, and allows one to consolidate thoughts and memories (Dement, 1999). REM sleep is also thought to help with learning, memory, and possibly creativity.
NREM: 75-80% of sleep
- Stage 1 (alpha brain waves): the time between being awake and just falling asleep; a very light sleep
- Stage 2 (sleep spindles and K-complexes): onset of sleep when the body starts to relax and physiological changes take place: regulation of heart rate and breathing, decrease in body temperature; about 50% of NREM is spent in Stage 2
- Stages 3 & 4 (slow-wave sleep): deeper stages of sleep when body tissues are repaired and energy is re-stored; growth hormone is typically released; when one may be difficult to awaken
REM: 20-25% of sleep
- Brain is active, loss of muscle tone and reflexes, vivid dreams occur, eyes move quickly back and forth and hence the name rapid eye-movement (REM)
Sleep starts in NREM and then alternates between NREM and REM sleep every couple of hours throughout the duration of sleep. The amount of REM sleep during each cycle increases in length over time, with the majority of REM sleep occurring during the last third of the sleep episode (Dement, 1999). It is worthy to note that people with sleep or other disorders may not follow the typical pattern of sleep stages. People with depression enter into REM sleep sooner and therefore have less NREM sleep and may have decreased growth hormone because of this. Also, a person who has narcolepsy enters directly into REM sleep instead of starting in NREM. Narcolepsy is a sleep disorder characterized by poor control of the sleep-wake cycle and manifests as frequent uncontrolled sleeping episodes.
The sleep-wake cycle is balanced between two major processes, one that promotes sleep and one that maintains wakefulness. The interplay between the brain and brainstem via neurotransmitters, neuromodulators, or hormones helps regulate the sleep-wake cycle. Adenosine, galanin, gamma-aminobutyric acid (GABA), and melatonin encourage sleep, while acetylcholine, dopamine, histamine, norepinephrine, orexin, and serotonin promote wakefulness. Sleep occurs primarily when the wakeful system wanes and the drive for sleep takes over. The need for sleep is called the homeostatic drive for sleep and increases throughout the day and decreases as sleep is achieved (Dement, 1999).
Sleep normally functions on a circadian rhythm, a 24-hour daily rhythm, which applies to both behavior and physiology. A region in the brain, called the hypothalamus, regulates the circadian rhythm by integrating multiple types of information including light cycles, eating times, hormones, stress, and temperature (Saper et al., 2005). The hypothalamus also regulates the secretion of melatonin from the pineal gland in response to light and dark stimuli.
Melatonin is a neurotransmitter that influences the sleep cycle and induces sleepiness. Regulated by the hypothalamus, the pineal gland secretes melatonin at the onset of darkness and peaks between 2:00 a.m. and 4:00 a.m. (Gooley et al., 2011). Basically, melatonin acts as a hormone and tells the body when it is dark or time to sleep (Saper et al., 2005). Adenosine is thought to be a key factor for driving sleep and builds up during the day. Recall from bio-chemistry that adenosine is a by-product of energy metabolism. Also, cortisol levels decline at the end of the day and then increase by morning to promote alertness. Stressful events or lifestyles can lead to an imbalance in the normal pattern of cortisol, a stress-response hormone, and contribute to insomnia, especially early awakening.
Sleep Needs and Age Differences
Adequate sleep has been defined from 7-9 hours a night and the exact amount needed for each person varies depending on factors such as general health, diet, and age (Watson et al., 2015; Colten and Altevogt, 2006). Although the need for sleep for an individual varies and is somewhat subjective, observational studies have shown when people are allowed as much sleep as they like, they tend to prefer between 7 and 9 hours of sleep. Children need more sleep, in general, because they are growing and developing. Newborns may sleep up to 16 hours a day and spend about 50% of sleep in REM. During the teen years, there is a tendency to have a later peak level of melatonin around midnight or 1:00 a.m., and therefore sleep onset is delayed from a typical schedule of sleep at 10:00 or 11:00 p.m. As people age, the amount of time spent in Stage 1 and 2 of NREM sleep decreases as well as quantity of REM sleep. It is unclear why sleep decreases in older adults, but it may be partly due to decreasing levels of melatonin (Klerman et al., 2013). The table below shows the National Heart, Lung, and Blood Institute recommendations for sleep by age or life stage. In general, it is recommended that adults get 7-8 hours and children at least 10 hours per night.
|Age or Life Stage||Recommended Amount of Sleep|
|Newborns||16–18 hours a day|
|Preschool-aged children||11–12 hours a day|
|School-aged children||At least 10 hours a day|
|Teens||9–10 hours a day|
|Adults (including the elderly)||7–8 hours a day|
|Source: National Heart, Lung, and Blood Institute, 2014|
Insomnia is the most commonly reported sleep disorder and occurs when there is a lack of sleep quantity or quality (Morin et al., 2012; Ohayon, 2002). More specifically, insomnia occurs when one has difficulty falling asleep, staying asleep, or is having early morning awakenings when there is ample opportunity for adequate sleep (APA, 2013). Insomnia can be further defined as non-restorative sleep when one doesn’t feel adequately rested after sleeping the recommended amount of time, indicating a lack of sleep quality.
Insomnia can be acute, intermittent, or chronic. Acute or short-term occurs over days or weeks while chronic or long-term occurs for at least a month and can go on for years (Morin et al., 2012). According to the Diagnostic Statistical Manual of Mental Disorders (DSM-V), the sleep issue needs to occur for three or more nights a week for three or more months to be classified as insomnia (APA, 2013). In the past, insomnia was described as primary (no other causes) or secondary (due to an underlying medical condition). However, the term primary insomnia has been replaced by insomnia disorder to avoid differentiating between primary and secondary insomnia (APA, 2013).
Prevalence of Insomnia
Many people have experienced symptoms of insomnia at some time in their life, with up to 50% of the U.S. population reporting symptoms each year (Walsh et al., 2011). Additionally, it is estimated that approximately 6% of the general population meets the DSM-V criteria for insomnia (Ohayon, 2008). Although insomnia can occur in anyone, it occurs more frequently in women and in people over the age of 65 years old.
Types of Insomnia
- Initial insomnia, sleep onset, or difficulty initiating sleep: People who have trouble falling asleep have increased sleep onset latency, which is defined as taking longer than 20 minutes to fall asleep. On the other hand, if people fall asleep too quickly, they may have sleep debt, meaning they are sleep-deprived and exhausted and, therefore, fall asleep faster than 20 minutes.
- Middle insomnia, sleep maintenance, or staying asleep: When there is difficulty staying asleep through the night, sleep quality as well as quantity decreases.
- Late insomnia or early awakening: The classic time for early morning awakening, usually due to stress or worrying, is between 2:00 a.m.-5:00 a.m., and the person often has trouble falling back asleep.
Symptoms of insomnia can include daytime sleepiness, fatigue, depression, poor concentration, memory issues, irritability, confusion, and changes in appetite. Insufficient sleep can result in delayed reaction times, decreased productivity, difficulty making decisions, and decreased immune function (Colten & Altevogt, 2006). Sleep loss is correlated with other illnesses including heart disease, diabetes, anxiety and depression, and obesity (Colten & Altevogt, 2006). Numerous studies show a positive correlation between increased body mass index (BMI) and sleep loss (Patel, Malhotra, White, Gottlieb, & Hu, 2006). One study showed that those who slept 5 hours or less, compared to people who slept 7-8 hours a night, were more likely to be obese (Patel et al., 2014 and 2006). During sleep the body makes leptin and ghrelin, hormones that influence appetite. Further research will help us understand more about how these hormones and others are impacted by insomnia and how that influences appetite, body weight, and obesity.
Understanding the Causes of Insomnia
Insomnia is a common sleep disorder and can be difficult to correct because the underlying causes are often multi-factorial and may be longstanding. The factors that can influence sleep include lifestyle, dietary habits, mental health issues, underlying medical conditions, and stress. A thorough understanding of the contributing causes is central to improving sleep, including, behavioral, psychological, or social factors. Additionally, a full evaluation by a medical professional is recommended for anyone who has chronic insomnia. It is important to make sure there is not an undiagnosed underlying condition. There are many potential causes including hormonal imbalances, sleep apnea, mood disorders, or heart and lung conditions.
Today’s modern world has many stressors and demands that impact people’s lifestyles and, potentially, sleep. Therefore, a thorough history and understanding of the pattern of insomnia can help determine and address the underlying cause. It may be helpful to maintain a sleep log to get an overview of the sleep-wake pattern, for example: frequency of occurrence, precipitating factors, and what makes it better or worse. It is recommended to maintain a sleep log for at least a week to assess the pattern and contributing factors (NSF, 2012). Also, creating a table or graph will help view the patterns or issues at a glance.
A typical sleep log might include :
- How long it took to fall asleep
- Wake and sleep times
- Quality of rest after sleeping
- Number of sleep interruptions
- Type of sleep interruptions (pain, pets, partners, worry, etc.)
Note: Consider adding a food diary to track dietary patterns including alcohol, caffeine, and sugar intake.
Other Contributing Factors
People who suffer from sleep issues may have stressful lifestyles, busy schedules, consume excessive caffeine or alcohol, travel frequently, keep an irregular sleep schedule, or have medical conditions such as depression, heart disease, obesity, or diabetes. Some common triggers for acute insomnia include physical or mental stress, anxiety, shift work, some medications, and travel across time zones. Lack of sleep can increase stress and stress can increase insomnia which can make breaking the cycle challenging.
In women, progesterone level can impact sleep. Progesterone is increased during the latter half of the menstrual cycle so may provide for more restorative sleep. Also, the decrease in progesterone at the beginning of the menstrual cycle may decrease sleep quality. Similarly, decreases in progesterone in menopausal women may contribute to the inability to sleep.
The initial step in addressing insomnia should begin with appropriate behavioral modification, as this is often the cause or a contributing cause. Acute or chronic insomnia can potentially be remedied by working on exercise, dietary, behavioral, and environmental factors. This may include establishing a regular sleep-wake schedule and a regular exercise program, having the proper sleep environment as well as avoiding stimulants like caffeine, nicotine, and alcohol. Resolving insomnia requires a multipronged approach and patience, since many factors can only be changed in small increments. The approach to improving sleep may vary depending on the type of insomnia.
Conventional Medical Treatment
Typical treatment includes: cognitive behavioral therapy for insomnia (CBT-I), sleep hygiene (lifestyle modifications to assist with improved sleep), and medications [antidepressants, GABA receptor agonists (benzodiazapines or ‘Z’ drugs (zaleplon, zolpidem, zoplicone) and over-the-counter medicines, like antihistamines] (Schutte-Rodin, Broch, Buysse, Dorsey, & Sateia, 2008). CBT-I is a specific type of cognitive behavioral therapy for insomnia, which address-es behavioral issues and, thus, potentially has a lasting impact (Garland et al., 2012; Mitchell, Gehrman, Perlis, & Umscheid, 2012; Morin, et al., 2012). Medications can have short-term benefit; however, they often have side effects such as amnesia, rebound insomnia, as well as cognitive effects. For example, GABA receptor agonists decrease REM and deep sleep. It is important to work with the client’s physician if the client is taking medications for insomnia.
Both research and clinical experience suggest that the following dietary considerations may be helpful in addressing insomnia:
- Magnesium-rich foods: Increasing magnesium-rich foods may be helpful as magnesium acts as a GABA agonist and N-methyl-D-aspartic acid (NMDA) antagonist. Assessing magnesium intake and absorption in the diet is especially important in the elderly since intake has been historically low in this population (Ford & Mokdad, 2003). One study demonstrated objective and subjective improvement of sleep with magnesium supplementation of 500 mg for 8 weeks (Abbasi et al., 2012). Magnesium-rich foods include dark leafy greens, legumes, grains, fish, and nuts and seeds. Aim for a minimum of 300-500 mg of magnesium per day.
- Tryptophan-rich foods: Foods rich in the essential amino acid, L-tryptophan, may be helpful. Tryptophan is a precursor to serotonin, which is used to make melatonin. Melatonin is important in maintaining the circadian rhythm. A tryptophan-rich breakfast combined with daytime light exposure promotes melatonin secretion in the evening (Fukushige et al., 2014). Tryptophan is abundant in many foods, including poultry, dairy foods, nuts, seeds, bananas, and eggs. A varied whole foods diet will likely supply adequate amounts of tryptophan. Consider experimenting with a tryptophan-rich breakfast along with a light carbohydrate-rich snack late in the day. The carbohydrates enable the tryptophan to be more available to the brain (NSF, 2012).
- Bedtime snacks: Eating a light, healthful snack can be helpful a few hours prior to bedtime to help stabilize blood sugar through the night for clients who have early morning awakenings. An ideal snack would be carbohydrate-rich with a small amount of protein. In general, it is best to avoid heavy meals within 3 hours of bedtime so keep portions small.
- Tart cherry juice: A few studies have looked at the usefulness of supplementing with tart cherry juice because it contains melatonin. These studies showed some usefulness, however the studies were small and behavior modification is more effective (Howatson et al., 2012; Pigeon, Carr, Gorman, & Perlis, 2010). More studies need to be completed to assess the usefulness of recommending tart cherry juice as a supplement to improve sleep; however eating cherries may be helpful for some.
- Caffeine: Caffeine from sources such as coffee, tea, sodas, or chocolate should be decreased or eliminated, especially after 3:00 p.m. Caffeine is thought to decrease sleepiness by inhibiting adenosine receptors. Limit caffeine intake to ½ cup or 1 cup of coffee or tea per day. Some people are more sensitive to caffeine so this will vary depending on the person and the specific circumstances.
- Alcohol: Alcohol intake, especially in the evening, can disrupt sleep. Alcohol acts as a sedative initially but then, as the body processes the alcohol, it becomes a stimulant and can interrupt sleep. Alcohol decreases deep sleep and REM sleep so, although it may help with falling asleep, it impacts the quality of sleep. Limit alcohol intake to no more than 1 serving for women and 2 servings for men per day.
- Fluid Intake: Consider limiting the amount of fluids consumed after dinner if waking for urination is interrupting sleep. Limit fluid intake 4-6 hours before bedtime; the amount of fluids and timing will vary by individual.
Modifiable Lifestyle Factors
Behavioral and lifestyle modifications are the primary intervention that should be implemented to re-establish a healthy sleep-wake routine as follows:
- Establish a regular sleep schedule: Create a ritual around bedtime to get the mind and body ready for sleeping. Try to go to bed and wake at regular times every day, even during the weekend and holidays. This will help your body maintain a regular sleep-wake schedule. It may be helpful to establish a routine or ritual; for example, brushing teeth, taking a warm bath, or reading in the same chair.
- Sleep environment: Ensure that the sleeping area is conducive to sound sleep, which includes making the room dark, quiet, and cool. Use the bed only for sleep and intimacy, and leave the bedroom when unable to fall asleep. After not being able to fall asleep for more than approximately 20 minutes, it is suggested to leave the bedroom, and then return to bed once sleepy and try again (NSF, 2012).
- Dark: Eliminate or decrease all light sources, including night-lights and alarm clocks. Utilize heavy curtains or blinds as needed.
- Quiet: Eliminate noises as much as possible. Consider if a pet or partner are impacting sleep and find creative solutions. Some find it helpful to use a fan or a white-noise maker to support undisturbed sleep. Additionally, earplugs can be useful.
- Cool: The body prefers to sleep at a cool temperature. Dress lightly and ensure the bedding and room temperature are supportive for sleep. The suggested temperature is approximately 65 degrees Fahrenheit. Experiment with what works best, since each person is unique.
- Be Comfortable: Use pillows to support the body if needed for comfort. Consider consulting with a physical therapist or health professional to discuss the best placement for pillows. Whether a bed is firm or soft is an individual preference and will vary. Clothing and sheets are best if they are breathable materials such as cotton, down feathers, or wool.
- Light/Dark: Studies show that exposure to early daytime light and avoiding synthetic light after sundown can help balance melatonin levels to encourage healthful sleep.
- Early daytime or morning light exposure can help reset the circadian rhythm so that it is easier to fall asleep at night. Suggestions include walking in the morning as part of an exercise program or sitting near a bright window to get exposed to morning light. Ideal exposure time is soon after waking for 30 minutes to 3 hours (Gooley, et al., 2011).
- Synthetic light exposure at night can disrupt the normal sleep cycle. Avoid light from artificial sources such as televisions, computers, tablets, and smartphones 1-2 hours before bedtime when possible.
- Exercise: Regular exercise can promote sleep, primarily, by assisting with stress management.
- Early morning or daytime is the best time to exercise. Evening exercise can work for some, especially if it is not vigorous. Strenuous exercise during the evening hours can be stimulating, however, getting regular exercise is most important. Good alternatives to vigorous exercise include yoga and walking.
- Relaxation techniques: Utilizing techniques to decrease stress and promote relaxation may be helpful especially for people having trouble falling asleep and for those dealing with stress or anxiety. Consider relaxation or meditation audio recordings to help induce sleep. Learning and practicing visual imagery, meditation, progressive muscle relaxation, or breathing exercises may also be helpful. Avoiding stimulating activity at night and adding relaxation techniques can work together to support restful sleep.
- Naps: Napping may be useful on occasion for those who are lacking sleep. Care must be taken since for some, napping may disrupt the circadian rhythm and make it difficult to fall asleep later. The general recommendation is to take naps in the early afternoon and to limit naptime to approximately 20 minutes (NSF, 2012).
- Tobacco: Avoid tobacco or nicotine use, especially close to bedtime.
Herbs and Supplements
Herbs and supplements may be helpful for some people as an adjunct to changes in behavior and lifestyle as follows:
- Herbs: In order to address anxiety-based causes of insomnia, consider replacing caffeinated drinks with calming herbal teas such as chamomile, valerian, hops, or other bedtime relaxing herbal teas. Concentrated herbal preparations such as valerian, dried extract or tinctures might be helpful; however, more research is needed to understand dosage, possible side effects and drug interactions(Leach & Page, 2014).
- Dietary Supplements: Melatonin 0.1 to 3 milligrams at night, limited to short-term use, may be helpful for some (Wilson et al., 2010; Murray & Pizzorno, 1998). Research shows melatonin to be most effective for jetlag-induced insomnia. Precautions: Melatonin can cause side effects in some people including: daytime drowsiness, vivid dreams or nightmares (Wilson et al., 2010). Begin with the lowest dose and take only short-term, as safety studies have shown melatonin to be safe for up to 6 months, but long-term studies have not been done, so use with caution (Wade et al., 2011).
Sleep is an essential part of optimal health and sleep disorders, especially insomnia, are prominent in today’s fast-paced culture. Outlined above are some safe and effective interventions that can have a positive impact in improving sleep and addressing insomnia. Central to achieving success is the combination of understanding the causes and adapting as needed with some trial and error, persistence, and patience.
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