We spend approximately one-third of our lives sleeping, although the amount of sleep and quality of sleep varies widely depending on age and other physiological factors. Most adults need 7-8 hours of sleep a night to reap the benefits of sleep and avoid the consequences of not getting enough sleep. Although sleepless nights every so often are not a cause for concern, insomnia can arise when it is difficult to sleep or stay asleep for an extended period. Here, we will identify the importance of sleep, outline the causes and consequences of chronic difficulties with sleeping, and provide some recommendations for treating insomnia.

What are the two types of sleep?

There are two types of sleep: non-rapid eye-movement (NREM) and rapid eye-movement (REM) sleep. During normal sleep, we cycle through both types of sleep, and dreaming typically occurs during REM sleep. Interesting fact: in order to prevent us from acting out our dreams, our brains temporarily paralyze our muscles. This is why sometimes, when we wake up, we have a feeling of not being able to move for a few seconds!

Although the importance of alternating between NREM and REM sleep is not well understood, there are many benefits of a good night’s rest — including cardiovascular, respiratory, hormonal, and metabolic benefits. A good night’s sleep also helps with muscle repair and maintenance, which is important because having a good exercise regimen also boosts sleep hygiene. In addition, sleep plays a critical role in memory consolidation and improved general brain function. On a deeper level, a good night’s rest can help clear harmful buildup of proteins, such as amyloid-beta, which is widely implicated in Alzheimer’s disease. Therefore, it is not surprising that not getting enough sleep can lead to all sorts of problems.

What is insomnia?

Although there is debate among scientists and clinicians about whether insomnia is a symptom or a disorder, the general consensus is to classify insomnia as difficulty sleeping or staying asleep. It’s important to note that many people experience acute insomnia, which can arise from stressful events such as procrastinating on a big project. This type of insomnia lasts for days or sometimes weeks and typically resolves on its own. However, chronic insomnia — arising from medical conditions, poor sleep hygiene, longer-term neurological stress, or long-term medication use — can last months or years and can be debilitating, leading to long-term physiological problems and increased risk for:

• Heart disease and stroke
• Diabetes and other metabolic disorders such as obesity
• Depression and other neurological conditions

Here are the common symptoms of insomnia:

• Difficulty falling asleep or staying asleep
• Not feeling well-rested after waking up
• Daytime sleepiness or drowsiness
• Irritability
• Difficulty focusing or remembering
• Impaired performance at work or school

What can cause insomnia?

Cognitive and physiological models of insomnia suggest that insomnia results from hyperarousal throughout the entire day. The cognitive model focuses on mental attributes leading to restless sleep, such as stress and worry, whereas the physiological model focuses on physical measures, such as metabolic rate, cardiovascular measures, neurological state, and neuroendocrine signaling. These physiological parameters can be assessed by measuring oxygen consumption, heart rate, hormone levels, glucose metabolism, and brain waves.

And what causes such daytime hyperarousal that’s behind insomnia? Unfortunately, there are many contributing factors, and oftentimes more than one factor is at play simultaneously. The causes of insomnia also vary based on age, genetics, and life events. Although not an exhaustive list, here are some of the more common causes:

• Stress or trauma. Having concerns about work, school, family life, health, finances, or other things can keep your mind active when it’s time to sleep.
  
• Shift work sleep disorder (SWSD). If you work at night or do not have a consistent work schedule, this can throw off your circadian rhythm, which is your body’s internal clock.
  
• Travel. Traveling across time zones can also throw off your body’s circadian rhythm, and frequent travel can lead to long-term sleep problems.
  
• Poor sleep hygiene. Not sleeping at a regular time, using electronic devices without a blue light filter, and doing stimulating activities before going to sleep can prevent you from falling asleep. In addition, using the bedroom for activities other than sleep can weaken the association between the bedroom and sleep, leading to more restless nights.
  
• Dietary choices. Eating too close to bedtime or drinking too much caffeine later in the day can cause you to stay awake longer than you’d like. In addition, substances such as alcohol and nicotine are linked to insomnia. The January app offers unique insight into how your diet and the times at which you eat can impact your sleep quality. Check out January here for more info.
  
• Genetics. It turns out that genetics can contribute to insomnia onset. Although the exact genes and genetic pathways are not currently known, many genes involved in neurotransmission are good candidates because of the roles they play in other neurological conditions such as depression and anxiety.
  
• Medications. Many prescription and over-the-counter medications can interfere with sleep. Even drugs prescribed for insomnia, such as benzodiazepines (e.g., Temazepam) and even the popular, “safer” nonbenzodiazepine sedative-hypnotic drugs (e.g., Ambien), when used over a long period of time, can actually worsen insomnia if individuals become too dependent on them, their efficacy wanes, and yet their side effects persist (and even worsen with age).
  
• Medical conditions. Chronic medical conditions such as cancer, diabetes, neurodegenerative diseases, and gastrointestinal disorders can disrupt sleep habits.

What are the health consequences of insomnia?

In general, several studies have found that people suffering from insomnia have higher metabolic and heart rates compared with controls. Similarly, serum levels of stress-related hormones, such as cortisol and adrenocorticotropic hormone, are generally elevated in insomniacs — especially during the evening and early parts of the night, although some studies have reported conflicting findings. These results suggest that lowering stress, eating healthy foods, and maintaining physical activity may be able to prevent insomnia.

Similarly, brain glucose metabolism is elevated in insomniacs in waking and NREM sleep states in areas of the brain that promote wakefulness, indicating that neural networks involved in wakefulness, such as arousal and emotion networks, may be abnormally active. This could also be due to overactivity of the locus coeruleus, an area of the brain that is the main source of the excitatory neurotransmitter norepinephrine. Interestingly, there are some medications that have an analog of norepinephrine listed in their ingredients, so be sure to check the label. Lack of sleep is also associated with an increase in amyloid-beta, which is a risk factor for developing Alzheimer's disease. 

How to cure insomnia?

All of this might sound glum, but thankfully there are steps you can take to treat and potentially cure insomnia. An important note here is that the efficacy of these suggestions is unique to each individual, and research is ongoing.

• Try cognitive behavioral therapy for insomnia (CBT-I). The effects of CBT-I on insomnia are largely dependent on the physiology of the individual, but in general CBT-I seems to improve outcomes and has become the favored “first-line” treatment option for insomnia at numerous leading teaching hospital systems. For example, CBT-I does not affect biomarkers such as cortisol and norepinephrine in patients with stable heart failure and insomnia, but these patients did report improvements in fatigue and sleep-related cognition. Similarly, pregnant women experiencing insomnia symptoms reported improvements in sleep efficiency and anxiety when completing a digital version of CBT-I.
  
• Implement a healthy diet. Eating a diet high in whole grains, fiber, unprocessed fruits, and omega-3 fatty acids is associated with a lower incidence of insomnia. In addition, eating foods high in tryptophan can make you sleep faster, probably through its role as a substrate for serotonin, a neurotransmitter that is a major sleep mediator. Milk, fish, turkey, chicken, and leafy greens are all great tryptophan options.
  
• Stick to an exercise routine. Moderate-to-high levels of exercise completed no later than a few hours before sleeping can promote sleep. Although this isn’t a quick fix, keeping to a routine over a longer period can help.
  
• Keep to a consistent sleep schedule. Yes, even on weekends! Doing this will train your body’s internal clock to sleep-wake times.
  
• Check your medications. Some medications contain compounds that can interfere with sleep, such as caffeine, corticosteroids, or pseudoepinephrines (found in some nasal decongestants). 

Key Takeaways

Sleep is essential to all aspects of health — from muscle healing to cognitive function. While short bouts of sleeplessness are not a cause for concern, insomnia is debilitating and can cause daytime sleeplessness, reduced metabolic rate, increased depression, and other symptoms that negatively impact your well-being. The onset of insomnia typically occurs with major life events that lead to alterations in brain structure and function, but it can also arise from lifestyle choices that are not conducive to good sleep hygiene. However, there is hope for you if you have insomnia; there are ways to treat it that include lifestyle changes, therapy (CBT-I, in particular), and (in some cases) certain medications. As always, work with your health care professional, who may refer you to a sleep specialist or sleep medicine center, to determine the right combination of potential remedies that will get you on the fast track to falling — and staying — asleep.

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