Motivation and emotion/Book/2011/Sleep and negative emotions
How can sleep effect our emotions?
Some people talk in their sleep. Lecturers talk while other people sleep. - Albert Camus
This chapter focuses on the relationship between sleep and the negative emotions of depression and anxiety.
Negative emotion is a term that could have a broad range of definitions. Hoyt and Yeater (2011) suggest a trait of negative emotionality very alike to neuroticism, it is defined as the tendency of intense anxiety, hostility, self-consciousness and impulsivity to be experienced by the individual. Negative affect proposed by Levin and Nielson (2007) also suggests a trait in which emotional distress is heightened and extreme behavioural expressions are more likely. Both of these descriptions involve negative emotions, but do not cover the whole of what is meant in this case by negative emotion. For the purpose of this chapter when the term negative emotion is used it means those emotions or states that are at an unhealthy level, such as extreme anger, pessimism, depression and anxiety.
There are two distinct types of sleep, rapid eye movement (REM) sleep and non-rapid eye movement (NREM) (Walker & Van der Helm, 2009). NREM sleep is divided into 4 stages from 1-4 with each stage representing a deeper stage of sleep (Walker & Van der Helm, 2009). REM and NREM sleep alternate in a cycle every 90 minutes throughout the night (Walker & Van der Helm, 2009). This cycle is mostly consistent for the duration of the night with some changes in the ratio of NREM to REM sleep (Walker & Van der Helm, 2009). NREM sleep in particular the 3rd and 4th stages are more prevalent in the first half of the night, while the 2nd stage of NREM and REM are more common in the later half (Walker & Van der Helm, 2009).
Sleep and emotion regulation
The area of sleep and its effects on emotion regulation has had only limited study. However this does not mean no study has occurred on the area, with studies showing findings that show the critical role sleep plays in emotion regulation (Walker & Van der Helm, 2009). The importance of sleep to regulate emotions is noticeable in that when sleep deprivation occurs irritability and affective volatility increase (Walker & Van der Helm, 2009). Sleep also plays a role in the level of reactivity the amygdala shows in response to emotion stimuli, when sleep deprived reactivity to negative emotional stimuli is increased (Walker & Van der Helm, 2009). Also a change in anticipation of negative events is seen when sleep deprived, with negative events being anticipated earlier by individuals that are sleep deprived (Walker & Van der Helm, 2009).
Sleep plays an important part in our emotional memory. Stimuli that trigger an individual's emotions are usually remembered better than if the stimulus was neutral, also events that have emotional and personal significance to the individual are remembered easily (Walker & Van der Helm, 2009). Studies using neuroimaging have found that the amygdala plays an important role in emotional memory encoding (Walker & Van der Helm, 2009). Further studies have found that part of this role is influencing medial temporal lobe structures, such as the hippocampal complex, for when emotional information is first received (Walker & Van der Helm, 2009). Sleep is involved in this memory formation in that emotional memory is better retained with sleep.
If sleep is deprived after a learning task, when the same task is performed the next day performance was impaired (Walker & Van der Helm, 2009). This effect was found to occur not from general sleep deprivation, but from REM sleep deprivation in particular (Walker & Van der Helm, 2009). However this provides some interesting possibilities for clinical use in particularly in relation to fear conditioning. If sleep is disturbed soon after learning the fear conditioning, consolidation is impaired (Walker & Van der Helm, 2009). If it is possible to decrease how well the fear conditioning was learned then it is possible a method of sleep deprivation could be used to help treat problems such as PTSD by decreasing the degree to which fear and other similar emotions would be consolidated (Walker & Van der Helm, 2009).
Waking up on the wrong side of the bed
Most of us have heard this phrase at some point in time, whether it was yourself providing a reason for a horrible day or someone else directing it at you because you've been a grump all day. Now why would people possible use a saying such as this to explain such things? And what do they mean wrong side, how does a bed have a wrong side to get out of? Quite simple, because it actually has to do with your sleep. When you're having one of those bad days and just forget important things (like having lunch with your best friend or getting the tickets to watch your favourite team in the grand final) you often wonder why. Well it's possible that the night before you didn't get enough REM sleep to help properly encode these emotionally significant events in your memory. What about when you're being a grouch, we can't blame that on lack of sleep too can we? Luckily we can, when you are sleep deprived the amygdala reacts more to negative stimuli, and also an increases anticipation of negative events. As such you are more likely to overreact to negative events and possibly expect more negative events to occur. Hence why everyone might have been calling you a grump this morning after you only got 4 hours sleep, and were yelling angrily at your house mate simply because they had eaten the last of the cornflakes. The good news is that getting a good night's sleep will help to prevent waking up on the wrong side of the bed again .
Sleep and depression
Depression is one of the most common mood disorders, with up to 90% of patients suffering sleep abnormalities (Walker & Van der Helm, 2009). Individuals with depression can have trouble going to sleep, oversleeping and waking up in the early morning or night time, as such they feel fatigue and sleepiness during the day (Koffel & Watson, 2009). Insomnia is a common risk factor for the beginning of depression and later recurrence (Walker & Van der Helm, 2009). Individuals with depression may also quickly fall into REM sleep, this has been associated with an increased risk of relapse (Walker & Van der Helm, 2009). Depression is characterised by high levels of negative emotionality or neuroticism and low levels of positive emotionality or extraversion (Koffel & Watson, 2009). In a study by Koffel & Watson (2009) it was found that insomnia was a good indicator of depression, however hypersomnia and fatigue were even more reliable indicators.
Sleep and anxiety
Two specific types of anxiety use sleep related symptoms: generalised anxiety disorder and posttraumatic stress disorder (Koffel & Watson, 2009). Generalized anxiety disorder is characterised by excessive worrying, irritability, trouble concentrating and muscle tension (Wetherell, Le Roux & Gatz, 2003). Sleep related symptoms of generalized anxiety disorder are a difficulty falling or staying asleep and poor quality sleep with fatigue during the day (Koffel & Watson, 2009). Evidence has been found that suggests that sleep problems early in life are a predictor of anxiety and anxiety disorders later on (Alfano, Pina, Zerr & Villalta, 2010). Frequent nightmares are associated with anxiety symptoms particularly in children, the occurrence of nightmares can cause the child anxiety before going to bed, further increasing any sleep disturbances they already have (Levin & Nielson, 2007).
Nightmares and our emotions
Nightmares are one of the most common forms of disturbed dreaming, they can vary in their effect on our emotions however it is possible for a nightmare to cause emotion escalated to the height of extreme terror (Levin & Nielson, 2007). The emotions nightmares cause can be simple and harmless, however some can be comparable to psychotic episodes with the severity of the emotion they cause (Levin & Nielson, 2007). Though nightmares occur occasionally in the general population it is often underestimated how common more severe nightmares can be, as roughly 4-10% of people are being affected by nightmares that are distressing and occur frequently (Levin & Nielson, 2007).
Nightmares usually occur during REM sleep, however they may occur in the 2nd stage of sleep when there are certain circumstances (Levin & Nielson, 2007). Nightmares can usually be divided by whether they are related to some trauma that has occurred, either by replicating the trauma or referring to it, or those nightmares which have no obvious relation to any trauma (Levin & Nielson, 2007). Nightmares are described as dreams which are disturbing enough to wake the sleeper, as opposed to a bad dream which will not wake the sleeper (Levin & Nielson, 2007).
Levin and Nielson (2007) propose a framework that explains the range of disturbed dreaming, two of the central concepts of this framework are affect load and affect distress. Affect load is stated as being the variations of emotional pressure that occur daily, affect distress is a disposition where events are more likely to be experienced with highly reactive emotions that are distressing (Levin & Nielson, 2007). It is the influence of these two concepts that result is variations in the prevalence, severity and frequency of nightmares (Levin & Nielson, 2007). Affect load is increased by rises in stress and negative emotions, thus interpersonal conflicts or heavy demands on memory may increase affect load (Levin & Nielson, 2007). When an individual is susceptible to a high affect load nightmares can become more frequent, this is supported by studies that have found increased life stress or specific stressors such as pregnancy or taking a fake intelligence test resulted in an increase in the frequency of nightmares (Levin & Nielson, 2007).
Affect distress is seen as a long lasting trait where emotional distress is heightened and the individual is more likely to react with behavioural expressions that are extreme (Levin & Nielson, 2007).It is proposed that affect distress in relation to nightmares occurs both when awake and sleeping, this highlights that intense emotional reaction occur to the sleeper not simply upon waking from a nightmare but also during (Levin & Nielson, 2007; Nielson & Levin, 2007). This distress along with the prevalence and frequency of nightmares can lead to mental health problems (Levin & Nielson, 2007).
Nightmares and personality
Studies have found contradicting evidence about personality traits in relation to nightmares, while some studies find a link between nightmares and neuroticism, others do not (Miro & Martinez, 2005). This inconsistency could come about for several reasons, differences in nightmare evaluation, the samples used and also the criteria that is used to define what a nightmare is (Miro & Martinez, 2005). Miro and Martinez (2005) conducted a study looking at the relation between nightmare frequency and certain personality traits, neuroticism and psychoticism, and also other possible affecters, anxiety and depression.
It was found that when nightmares occur on a monthly basis there were links to personality traits in particular psychoticism, with no link to sleep quality, anxiety or depression (Miro & Martinez, 2005). In comparison when nightmares occurred on a weekly basis there was a strong connection with those participants that showed a depressed mood (Miro & Martinez, 2005). There was no evidence in this study of links between nightmare prevalence and anxiety or neuroticism (Miro & Martinez, 2005).
Nightmares and PTSD
A health problem that is commonly associated with nightmares is posttraumatic stress disorder (PTSD) (Levin & Nielson, 2007). Nightmares and dysfunctional REM sleep are strong indicators of PTSD, other similar indicators are lower sleep quality and sleep disturbances that occur frequently (Levin & Nielson, 2007). Nightmares associated with PTSD often involve a replication or reference to the trauma that was experienced (Levin & Nielson, 2007). Nightmares occur in roughly 90% of individuals that are effected by PTSD, with nightmares occurring up to a possible 6 times a week (Levin & Nielson, 2007). It has also been found that nightmares occurring before a trauma can predict the severity of PTSD, this implies that the presence of nightmares may indicate a risk towards psychopathology, such as PTSD, when trauma is experienced (Levin & Nielson, 2007). Also when nightmares began to occur immediately after a trauma it was found that the individuals later had severe PTSD symptoms that were worse than other individuals that had not had the nightmares (Levin & Nielson, 2007). These findings indicate that nightmares are closely linked to PTSD as a primary symptom and also as a predictor of the development of PTSD after a trauma (Levin & Nielson, 2007).
I love sleep. My life has the tendency to fall apart when I'm awake, you know? - Ernest Hemingway
- Some interesting points
- Nightmares are more common in women, this difference is maintained across the lifespan, however it is still unclear why this difference occurs (Levin & Nielson, 2007).
- Nightmare frequency and distress has been related to health problems such as allergies, gastric problems and pain (Levin & Nielson, 2007).
- Nightmares associated with PTSD can continue to occur 40-50 years after the trauma (Levin & Nielson, 2007).
Alfano, C. A., Pina, A., Zerr, A. & Villalta, I. A. (2010). Pre-Sleep Arousal and Sleep Problems of Anxiety-Disordered Youth. Child Psychiatry and Human Development. 41(2), 156-167. doi: 10.1007/s10578-009-0158-5
Hoyt, T. & Yeater, E. A. (2011). The Effects of Negative Emotion and Expressive Writing on Posttraumatic Stress Symptoms. Journal of Social and Clinical Psychology. 30(6), 549-569. doi: 10.1521/jscp.2011.30.6.549
Koffel, E. Watson, D. (2009). The two-factor structure of sleep complaints and its relation to depression and anxiety. Journal of Abnormal Psychology. 118(1), 183-194. doi: 10.1037/a0013945
Levin, R. & Nielson, T. A. (2007). Disturbed dreaming, posttraumatic stress disorder, and affect distress: A review and neurocognitive model. Psychological Bulletin. 133(3), 482-528. doi: 10.1037/0033-2909.133.3.482
Miro, E. & Martinez, M. P. (2005). Affective and Personality Characteristics in Function of Nightmare Prevalence, Nightmare Distress, and Interference Due to Nightmares. Dreaming. 15(2). 89-105. doi: 10.1037/1053-07188.8.131.52
Nielson, T. A. & Levin, R. (2007). The dimensional nature of disturbed dreaming: Reply to Weiss (2007). Psychological Bulletin. 133(3), 533-534. doi: 10.1037/0033-2909.133.3.533
Walker, M. P. & Van der Helm, E. (2009). Overnight therapy? The role of sleep in emotional brain processing. Psychological Bulletin. 135(5), 731-748. doi: 10.1037/a0016570
Wetherell, J., Le Roux, H. & Gatz, M. (2003). DSM-IV criteria for generalized anxiety disorder in older adults: Distinguishing the worried from the well. Psychology and Ageing, 18(3), 622-627. doi: 10.1037/0882-79184.108.40.2062