How sleep and mental health affect each other
How Is Mental Health Related to Sleep?
Even though science has provided many answers regarding sleep and its functions, there is still a lot of unknown. We know that sleep is important (especially if we don't sleep well), but we do not exactly know what is going on during sleep.
Sleep could be defined as "reversible disengagement and unresponsiveness to the external environment, regularly alternating in a circadian manner with engagement and responsiveness" (Abdullah, 2022; pp. 1).Good sleep is positively related to physical and mental health. But what is good sleep? Sleep duration and sleep quality are often used as indicators of good sleep (Abdullah, 2022). Sleep duration change with age, decreasing from infancy to older children and becoming less or more constant during adulthood. However, it is important to note that there are individual differences regarding sleep duration. Some people naturally need more sleep, while others feel fully rested after only a few hours of sleeping. Finally, sleep quilty is often described as a subjective estimation of rest after sleeping. Other indicators of the quality of sleep (Ohayon et al., 2016) are listed below:
Sleep latency - based on expert opinions, a sleep latency of 45 - 60 minutes is an indicator of poor sleep quality among both kids and adults (except older adults where a sleep latency of more than 60 minutes indicates poor sleep quality).
The number of awakenings during the night (lasting more than 5 minutes) - it is considered that 0 or 1 awakening (i.e., 2 for older adults) is an indicator of good sleep quality.
Waking up after sleep onset - based on the expert opinion, for all age groups waking up 20 or fewer minutes after sleep onset is an indicator of good sleep. However, waking up after 46 or more minutes (except for older adults) is an indicator of poor sleep quality.
Sleep efficiency - is defined as the ratio of total sleep to time spent in bed. It is considered that sleep efficiency of 85% and higher indicate good sleep quality in all age groups.
More detailed information about sleep quality could be derived from the analysis of sleep architectures and sleep patterns represented as non-REM and REM phases that occurs during sleep.
Common sleep problems
Some studies (for review, see Staner, 2022) showed that one-third of the population has sleep disturbance. Based on data from the USA (Chokroverty, 2010), 35% of people from the general population are reporting a problem with falling and staying asleep, waking up early in the morning, or having a nonrestorative sleep, while 10% experience insomnia. Sleep apnea is present in 3 to 4% of the population, while daytime sleepiness is experienced in 1 of 5 people. In other world, millions of people around the world are dealing with some sleep difficulties that negatively impact the quality of their life.
Why is sleep so important to our mental health?
Previous studies showed that sleep insufficiency has numerous negative health consequences both in children and adults. In children, sleep deprivation was associated with problems with focusing, lower school performance, problems in socialization, and low self-esteem. Similar effects are seen in adults. Additionally, it seems like poor sleep quality in adults also could be a risk factor for developing some physical illnesses, such as cardiovascular disease and type 2 diabetes (Abdullah, 2022). All this together will, of course, negatively impact subjective well-being.
How does sleep affect your mental health?
We all know that even one night of poor sleep could make us moody, easily annoyed, and distracted. Poor quality of sleep negatively affects our emotions and cognition. The inability to focus and slower response time could negatively impact not just our productivity but also endanger our life. Additionally, a growing body of literature shows that sleep problems could also occur as symptoms of various mental disorders.
Numerous studies confirmed the link between sleep and depressive symptoms. Even diagnostic criteria (for example, DSM-V) for depression include sleep disturbances (hypersomnia or insomnia) as one of the symptoms.
Available data shows that even 40% of people dealing with insomnia also meet the criteria for clinical depression, while 80% of people with depression also report insomnia (Zweerde et al., 2017). Although underlying mechanisms are not yet fully explained, it is clear that poor sleep could worsen depressive symptoms and, therefore, should not be taken lightly. Knowing all of that, it is not surprising that it was shown that insomnia treatment could also be beneficial for the reduction of depressive symptoms (Zweerde et al., 2017).
Seasonal Affective Disorder
Seasonal affective disorder is another mood disorder that typically occurs during the fall and winter months. Typical for seasonal affective disorder is the fact that remission happens spontaneously during spring and summer (Wescott et al., 2020). Again, sleep disturbance is also one of the frequent symptoms. However, in seasonal affective disorder, different sleep difficulties occur - hypersomnolence and delay in sleeping time. Interestingly, results of polysomnographic studies showed that people with seasonal affective disorder did not differ from the control group (unlike people diagnosed with nonseasonal mood disorders) (Wescott et al., 2020),
Each of us probably experienced at least once the inability to fall asleep in situations when we feel anxious or overly excited. It feels like our brains cannot turn off. Consistent with our subjective experience is data from numerous studies (for review, see (Staner, 2022) that showed that various sleep disturbances are very common in people with anxiety. Insomnia and nightmares are very frequent in generalized anxiety disorder (GAD) and posttraumatic stress disorder (PTSD). Sleep disturbances (both insomnia and hypersomnia) are also found in panic disorder and obsessive-compulsive disorder.
Typical for bipolar disorder is the occurrence of both elevated moods as well as depression. Sleep disturbance is present in both phases and negatively impacts the quality of life as well as treatment outcomes. During the manic episode, the reduced need for sleep is present in 69 to 99% of people diagnosed with bipolar disorder. They are also reporting that they also have problems with falling asleep as well as staying asleep. Contrary, during a depressive episode, sleep disturbance is usually manifested as hypersomnia (in 38 to 78% of people with bipolar disorder). Interestingly some people with bipolar disorder also report insomnia, and insomnia could predict the worse course of illness (for details, see Gold & Sylvia, 2016).
Attention deficit hyperactivity disorder (ADHD)
Sleep disturbances are often present also in people with ADHD. Based on parental reports, children with ADHD more often experience sleep difficulties compared to the control group. Typical sleep problems in children and adolescents with ADHD are bedtime resistance, delayed sleep onset and shorter sleep time, nightmares, sleepwalking, sleep paralysis, movement during sleep, etc. (Kirov & Brand, 2014).
Autism Spectrum Disorder
Poor sleep quality and sleep disturbance are common in children with an autism spectrum disorder. Sleep difficulties could be one of the first early signs of autism. Based on available data the occurrence of sleep disturbances in children and adolescents with autism varies between 32 and 71.5% (Deliens et al., 2015). Sleep disturbance in children with autism often persists in some form, even during adulthood.
One study (Zhou et al., 2022) showed an association between the number of hours of sleep and cognitive performance in elders. Namely, in this study, participants who reported that they are sleeping 8 and more hours also scored lower on one cognitive test (Mini-Mental State Examination - MMSE). The authors proposed an explanation for such a result stating that longer sleep might indicate poor sleep quality. Interestingly, this association seems to be gender-dependent, i.e., it was stronger in females.
Knowing that lack of sleep affects emotions and cognition, it is not surprising that the quality of our sleep could also impact our level of happiness. The study conducted in China (Zhao et al., 2019) showed that sleeping for less than six h was associated with a lower happiness score compared with the group who slept for eight or more hours, and that was particularly the case for younger people and females. Not surprisingly, this study also showed that some sleep difficulties (such as difficulty in falling and staying asleep as well as early awakening) were associated with lower levels of happiness. Finally, insomnia also predicted lower happiness levels, especially in older adults and females.
How does mental health affect your sleep?
As we mentioned before, it is still unclear what exactly is the causal relationship between sleep disturbance and mental disorders. However, it is evident both from the literature and practice that they often co-occur. Perhaps there is a common underlying cause for both sleep disturbances and mental disorders, or the presence of one worsens the other. Either way, experiencing mental health issues (or even just elevated stress) will certainly negatively affect your sleeping, which will further make your symptoms worse.
Ways To Improve Both Sleep and Mental Health
Acquiring a healthy and balanced lifestyle is the best way to improve the quality of your life and your physical and mental health. Although there is no quick, magic solution, there are several things that you can start practicing today.
- Healthy diet
A balanced diet could positively impact sleep quality. Numerous studies (for details, see Frank et al., 2017) identify specific nutrients that impact sleep. For example, it was shown that a lot of sugar, low fiber, and intake of high-saturated fat are associated with lower quality of sleep. Not just particular nutrients but also their combination affects sleep. For example, it was shown that a high-carbohydrate/low-fat diet was associated with poor sleep quality. Finally, not just what we eat but also when we eat could impact our sleep. Having high glycemic index carbohydrate food before sleep (i.e., 4h earlier) could help us fall asleep easier.
2. Better stress management
Stress is an inevitable part of our daily life, but we can learn how to manage it better. Improving our coping strategies, leading a more meaningful life, and making connections with others and the world around us could help us minimize the negative impact of stress. As a result, we will sleep better and overall feel better both mentally and physically.
Numerous studies showed the positive impact of exercise on mental health. For example, even during the recent COVID-19 pandemic outbreak, it was shown that exercise could decrease distress (Sokić et al., 2021). Additionally, some studies (e.g., Brand et al., 2013) showed that athletes experience fewer symptoms of depression compared to the general population. This is important because (as we already mentioned) sleep disturbances often occur in people dealing with depression.
4. No devices in your bedroom
Studies (e.g., Twenge et al., 2019) showed that the use of mobile devices before sleep could negatively impact your sleep. To be fair, we don't need a study to know that. Mindless scrolling for hours is a bad habit that affects not only our sleep but also our mood. Don't do it.
5. Read before bed
Reading before bed can actually improve your sleep by decreasing levels of stress, anxiety, and depression. Reading can also helps us feel less lonely.
More about the benefits of reading you can find in our previous article.
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