Motivation and emotion/Book/2016/Sleep and depression

Overview
We have all experienced periods of being sad or depressed at some point, which is normal given all of the responsibilities and struggles that we face in everyday life. Similarly, we have also experienced how it feels when we do not get adequate sleep. Think back to the days you were in high school or university. Did you find that you were staying up late at night studying? Did you find it overwhelmingly difficult to get out of bed the next morning? During the school day did you sometimes experience periods of low mood, fatigue, irritability, and found it hard to concentrate when you hadn't had a good nights sleep? Symptoms such as fatigue, low mood and irritability may present themselves after inadequate sleep, but also happen to be symptomatic criteria for the diagnosis of major depression (American Psychiatric Association, 2013). So is there a relationship between sleep and depression? Is it possible that too many late nights could put your psychological and physical health at risk?

What is depression?


Depression is a mood, which is marked by distinct feelings of sadness, hopelessness or anhedonia (inability to feel pleasure for once pleasurable activities) (Curry & Hersh, 2014). Depression is problematic in society as it affects millions of people globally; approximately 1 in 6 people will experience some level of depression in their lifetime (Beyond blue, 2016). It is also the leading cause of disability and suicide worldwide (Hollon, Thase & Markowitz, 2002). Depression can range from mild in severity (disrupting normal mood) to severe (impacting everyday functioning) (Hollon, Thase & Markowitz, 2002). More severe forms of depression are clinically diagnosed under the DSM-5 criteria including Disruptive Mood Dysregulation Disorder (DMDD), Major Depressive Disorder (MDD) and Persistent Depressive Disorder (PDD) to name a few (American Psychiatric Association, 2013). The most commonly diagnosed depressive disorder is Major Depressive Disorder; a debilitating psychiatric disorder where negative symptoms are present almost every day for at least 2 weeks and impact normal functioning (American Psychiatric Association, 2013).

Major Depressive Disorder is characterised by 5 or more of the following symptoms (American Psychiatric Association, 2013):
 * Feelings of sadness, emptiness or hopelessness
 * Loss of pleasure in activities once enjoyable
 * Feelings of worthlessness or guilt
 * Fatigue or loss of energy
 * Irritability or agitation
 * Insomnia or hypersomnia
 * Difficulty concentrating, indecisiveness
 * Significant weight loss or weight gain
 * Suicide ideation or recurrent thoughts of death

What is sleep?
Sleep is the body’s restorative mechanism and has many definitions but can be characterised as a state of unresponsiveness and inactivity to the environment, involving closed eyes (Kumar & Chanana, 2014). Sleep is essential for the body to fight infection, maintain homeostatic balance, optimise health, regulate mood and heighten cognitive function (Kumar & Chanana, 2014). Sleep consists of 2 parts that alternate cyclically during the period of its course known as non-rapid eye movement (NREM) and rapid eye movement (REM) (Colten & Altevogt, 2006). NREM is further divided into 4 individual stages comprising of specific brain wave patterns, eye movement and muscle tone. Generally, NREM will take place at the beginning of sleep consisting of stages 1 through to 4 followed by REM but will transition through the previous stages during the remaining episode of sleep (Colten & Altevogt, 2006). A standard night’s sleep is attributed to approximately 80-85% of NREM and 20-25% of REM with the first NREM-REM cycles lasting approximately 70-100 minutes. The second and later stages can be for between 90-120 minutes long (Colten & Altevogt, 2006).

Sleep disorders and abnormalities
Sleep disorders disrupt normal sleeping patterns and involve difficulty initiating sleep, maintaining sleep or frequent awakenings (insomnia), disorders of excessive sleepiness (hypersomnia), abnormalities in the sleep-wake cycle and dysfunctional sleep stages, dreams and arousal (parasomnia) (Cormier, 1990). Insomnia is the most common type of sleep disruption (Cormier, 1990). Sleep disturbances are problematic as they can adversely impact cognitive function, mood regulation, physical and psychological health and quality of life (Harvey, 2009).

Table 1. Sleep disorders (American Psychiatric Association, 2013)

Biological
Research on biological causes of depression suggests that depression is linked to chemical imbalances in the brain. Dysfunctions in the monoamine neurotransmitters dopamine, norepinephrine and serotonin are believed to impact mood and are likely a result of genetic vulnerabilities to depression (Ruhé, Mason, & Schene, 2007). All of these neurotransmitters are involved in wakefulness and sleep, and chronic sleep deprivation has been suggested to induce neurobiological change, predicting the development of depression and other psychiatric illnesses (Novati et al., 2008).

Table 2. Neurotransmitters and their relation to depression

Psychological


Psychological theories have proposed a variety of explanations for depression including cognitive, psychoanalytic, humanistic and behaviourist models to explain underlying thoughts and behaviours of the disorder. Cognitive theories, in particular, are useful for explaining the cycle of depressive thoughts and how this cycle of thinking is relevant to insomnia (Gupta, 2016).

The cognitive theory of depression focuses on the beliefs of an individual and emphasises that depression is a result of distorted thoughts and beliefs, irrational judgments and negative thinking biases which lead to a pessimistic thinking style (Gupta, 2016). Perhaps the most well-known cognitive theory of depression is Beck's (1967) cognitive triad model (see Figure 2). The cognitive triad model explains the three components of negative thoughts associated with depressed individuals- dysfunctional thoughts about the self (e.g; "I am a failure"), the future (e.g; "nothing ever improves for me") and the world (e.g; "no-one cares about me"). Based on this theory, thoughts are automatic and are exacerbated by the triad, making an individual vulnerable to depression (Beck, 1967).

So how does this relate to sleep? Insomnia sufferers often have dysfunctional beliefs and cognitive distortions similar to those found in depressive patients. A study by Gupta (2016) found that both insomnia patients with depression and without depression had the same dysfunctional beliefs in regards to presleep cognitions. The beliefs tend to ruminate and this, in turn, becomes a vicious cycle, worsening insomnia and causing worry and stress (Gupta, 2016). This is useful in understanding that sleep disorders often elicit depressive symptoms due to negative thinking, and negative thinking can cause sleeping difficulties.

Research linking sleep disturbances and depression


Sleep disturbances are one of the most prominent symptoms found in the diagnosis of depression, so common that some critics have argued a diagnosis of depression should not be made unless sleep complaints are present (Calandra, Luca & Luca, 2013). Patients often seek medical treatment for sleep disturbances and discover they also have depression due to the overlap of common symptoms (Nutt, Wilson & Paterson, 2008). Research shows there is a strong bilateral link between depression, sleep deprivation and sleep disorders (Kumar & Chanana, 2014){{expand]].

Sleep deprivation & depression
Sleep deprivation, also referred to as short sleep, is when time spent sleeping is less than the average number of hours required for a particular age group (Roberts & Duong, 2014). Evidence that sleep deprivation is associated with psychological and interpersonal functioning deficits, and can lead to more instances of depression, anxiety and suicidal ideations, particularly in adolescents (Roberts & Duong, 2014). Moreover, fatigue, lack of energy and other symptoms found in depressive disorders have been a reported as a result of sleep deprivation (Roberts & Duong, 2014). A study by Roberts, Roberts, & Chan (2009) investigated sleep deprivation among adolescent populations and discovered that sleeping less than 6 hours increased the risks for depressed mood, lower perceived life satisfaction and poorer perceived health in general.



Insomnia & depression
Chronic insomnia and depression are highly comorbid and constitute a problematic and complex relationship (McGlinchey, Reyes-Portillo, Turner, & Mufson, 2016). Approximately three-quarters of people who suffer from depression also suffer from symptoms of insomnia, with the greatest number of people being females (Nutt, Wilson & Paterson, 2008). Insomnia is one of the core symptoms of MDD and can be triggered by symptoms associated with depression such as negative affect or exhaustion (Australian Psychiatric Association, 2013). Moreover, insomnia can greatly exacerbate depressive symptoms, increase suicide risk and negatively impact quality of life (Nutt, Wilson & Paterson, 2008). It also can prevent patients from full remission of depressive disorders (Wagley, Rybarczyk, Nay, Danish, & Lund, 2012). Even without depression symptoms present, literature emphasises that people who suffer only insomnia have a greater risk of developing depression in the future (Nutt, Wilson & Paterson, 2008).

Hypersomnia & depression
Excessive sleep is also related to depression (Plante et al., 2012). The presence of hypersomnia or excessive sleep in MDD is a core symptom (Australian Psychiatric Association, 2013). Recent research has found that patients with hypersomnia occurrence in MDD had reduced parieto-occipital slow wave activity in comparison to patients without hypersomnia (Plante et al., 2012). This suggests that patients who are depressed often have reduced slow-wave sleep which causes them to feel unrefreshed even after sleeping for an adequate number of hours.

Parasomnia & depression
Polysomnographic research on sleep has hypothesised that depression is associated with disrupted regulation of REM sleep and decreased slow wave sleep (Palagini, Baglioni, Ciapparelli, Gemignani, & Riemann, 2013). Sleep changes such as reduced REM latency (time interval between sleep onset and first REM session), REM density (frequency of rapid eye movements) and increased time in total REM sleep are biological markers for depressive disorders and may be effective in predicting relapse and recurrence (Palagini, Baglioni, Ciapparelli, Gemignani, & Riemann, 2013). However, further experimental research is required in respect to REM sleep regulation and depression but conducting this research tends to be time-consuming and expensive.

Circadian rhythm irregularities & depression
The 24-hour sleep-wake cycle is comprised of two operating regulation processes - the circadian process and the homeostatic process (Calandra, Luca & Luca, 2013). The circadian process regulates rhythms of the brain and body, performing functions such as sleep-wake activity, liver function and hormone release. The homeostatic process, on the other hand, builds a quantitative ‘sleep debt’, resulting in increased pressure to sleep (Calandra, Luca & Luca, 2013). Sleep pattern irregularities in circadian rhythm cycles and homeostatic maintenance have been found in patients with depression (Nutt, 2008; Calandra, Luca & Luca, 2013).

So what does this all ultimately mean? Sleep and depression can be compared to the chicken and egg dilemma - which came first the chicken or the egg? Sleep problems influence depressive symptoms whilst depression influences sleeping problems. The relationship is like a two-way street; both feed off one another (Berk, 2009).

Treatment
A number of treatment options are available for depression and sleeping problems including pharmacological methods, cognitive behavioural therapy (CBT) and manipulation of sleep mechanisms such as the sleep-wake rhythm. Due to the intimate relationship between depression and sleeping problems, treating or managing depressive symptoms can help to improve sleep quality, while treating sleeping problems can relieve depressive symptoms during the day such as fatigue, sadness and reduced concentration (Berk, 2009).

Pharmacology
Pharmacological methods are often used to treat depression and insomnia. Selective serotonin reuptake inhibitors (SSRI) are the first-line treatment for depression, as serotonin has been extensively researched to be involved in both depression and sleeping disturbances (Nutt, Wilson & Paterson, 2008).The majority of antidepressant drugs suppress REM sleep, which decreases the amount of time spent in REM sleep and can improve depressive symptoms (Palagini, Baglioni, Ciapparelli, Gemignani, & Riemann, 2013). However, controversy arises as reanalysis of data has found some publication biases in the efficacy of approved anti-depressant medications (Hollon, 2012).

Cognitive-behavioural therapy (CBT)
CBT is a safe, effective treatment used both alone and in combination with other treatment methods for sleeping disorders, mainly insomnia (Morin, 2004). A recent meta-analysis reviewed the use of CBT for depressed patients and found it to be an equally efficacious treatment for depression compared with other forms of psychological treatment, as well as more cost-effective (Hofmann, Asnaani, Vonk, Sawyer, & Fang, 2012). CBT works by reducing false beliefs and dysfunctional thinking (Carney et al., 2010). A study by Tolin (2010) compared CBT as a treatment to other forms of psychotherapy in depressive disorders and was found to be superior compared to other psychodynamic therapies at post-treatment. CBT is regarded as a more beneficial long-term treatment for sleep improvements compared to pharmacological methods of treatment, due to its potential to help patients understand and eradicate the likely causes of insomnia (Morin, 2004).

Manipulation of the sleep-wake rhythm
Manipulation of the sleep-wake rhythm can reduce depression and help restore sleep regularity. Methods include light therapy, chronotherapy, sleep cycle manipulation and sleep-wake manipulation (Calandra, Luca & Luca, 2013). Light therapy treatment, for example, is effective by exposing a bright light in the morning to reset a delayed biological clock, thus reducing the difficulty of falling asleep at night time (Calandra, Luca & Luca, 2013). Treating sleep-cycles during the night can show sleep improvement for MDD patients in only a few hours (Calandra, Luca & Luca, 2013).

Improving sleep hygiene


Sleep hygiene is important in maintaining optimal health and combating depressive symptoms which can arise from poor quality sleep. Quality and quantity are equally important for sleep, as approximately 7-9 hours sleep for adults in needed for the body to rejuvenate itself and go through deep sleep stages of NREM sleep (National Sleep Foundation, 2016). Try some of the following tips for a better night sleep and to reduce your risk of developing depression and other psychiatric disorders (Berk, 2009):
 * Turn off all lights and reduce noise
 * Keep the temperature in the room cool
 * Avoid stimulating discussions or talks before bed
 * Avoid caffeinated drinks at least 8 hours before going to sleep
 * Avoid alcohol at least 8 hours before going to sleep
 * Avoid taking naps during the day, this can disrupt your sleep cycle
 * Exercise regularly each day
 * Keep the same routine each day and night
 * Try to go to bed and wake up at the same time each day

 {Which is not a symptom of depression? - Feelings of emptiness or despair - Feeling of hopelessness - Loss of interest in activities which were once enjoyed - Fatigue + Shortness of breath
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{How many hours sleep is recommended for adults? - 6-8 hours +7-9 hours - 8-10 hours - 9-11 hours - 11 + hours
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{What is the most common type of sleep disorder? + insomnia - hypersomnia - sleep walking - night terrors - none of these
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{Approximately how many people with depression also suffer from insomnia symptoms? - one-quarter of people - half of people + three-quarters of people - all of them - don't know
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Conclusion
Main points to take away from this chapter include:
 * There is a strong bilateral link between depression and sleep, as sleep disturbances can trigger depression and depressive symptoms, whilst depression can cause negative thinking patterns and lead to sleeping disturbances.
 * Sleeping for 6 hours or less can lead to problems with mood, cognition and lower life satisfaction, as well as increasing suicide risk
 * Treatments available for depression and sleep problems include medication, CBT and manipulation of the sleep-wake rhythm.
 * Sleep hygiene is important to reduce depressive symptoms associated with sleep deprivation and sleep disorders.