How Sleep Apnea Can Affect Mental Health: Links to Anxiety and Depression

Quick Takeaways

• Sleep apnea and mental health conditions like anxiety and
  depression may occur together and can influence each other.
• Disrupted sleep can trigger or worsen anxiety and depressive
  symptoms, while mental health conditions can make sleep apnea symptoms
  feel worse.
• Treatment for sleep apnea, such as continuous positive airway
  pressure (CPAP) therapy, may improve both sleep quality and mental
  health symptoms in some people.

An astounding 89% of people agree that getting enough sleep makes
them feel better about themselves and gives them more energy to spend
time with loved ones.¹ Unfortunately, sleep disorders like
sleep apnea, where breathing repeatedly stops and starts during
sleep,⁴⁵ can impact your mental and emotional well-being.
Understanding the connection between sleep apnea, anxiety and depression
may help you recognize important symptoms and seek the right care.

Understanding the sleep apnea and mental health connection

First, it’s important to understand these conditions before looking
at how they are connected. Sleep apnea can lead to pauses in breathing
that may last from 10 seconds to over a minute. These pauses can starve
your organs from getting oxygen.

Alternatively, obstructive sleep apnea (OSA) is a condition where the
muscles around the throat relax to the point of collapse, restricting
airflow during sleep. Breathing may become shallow or stop for seconds
to minutes at a time. Someone with OSA may experience:²⁵

• Excessive daytime sleepiness
• Morning headaches
• Feeling irritable or moody
• Difficulty concentrating, struggling to feel present during the
  day
• Snoring or gasping for air while they sleep

Anxiety causes people to feel overly nervous or worried about things
in daily life, and these persistent feelings or thoughts can interfere
with how a person lives their life. A person with anxiety
may:²

• Feel excessively worried
• Have a hard time concentrating
• Experience pain, including headaches and stomachaches
• Find it hard to relax
• Have trouble falling asleep or staying asleep

Depression is a condition that causes severe symptoms that can affect
a person’s mood, thoughts, feelings, and how they handle day-to-day
activities. Common symptoms of depression include:³

• Intense feelings of sadness, hopelessness, worthlessness or
  frustration
• Lack of energy
• Loss of interest in activities
• Trouble concentrating
• Pain, headaches or digestive issues
• Difficulty sleeping or sleeping too much

How sleep apnea and mental health influence each other

Sleep apnea and mental health conditions frequently appear together.
Studies show that about 35% of people living with obstructive sleep
apnea (OSA) also experience symptoms of depression. Similarly, 32% to
43% of people with OSA experience anxiety.^4,5

Depression and anxiety can also worsen sleep quality and complicate a
sleep apnea diagnosis, making it important to recognize and address both
sleep apnea and mental health conditions.

How sleep apnea affects the brain and mood

When breathing stops repeatedly throughout the night due to sleep
apnea, it keeps you from getting the deep, restorative sleep your brain
needs to function. Repeated breathing pauses can cause oxygen levels in
your blood to drop, changing how your brain controls mood.⁶
Your brain uses chemicals like serotonin and dopamine to help keep
emotions steady. When oxygen levels go up and down, that balance can get
thrown off.⁴⁶

Sleep apnea interruptions also disturb deep sleep and rapid eye
movement (REM) sleep, which are essential for mental health.⁷
REM sleep is when dreaming typically occurs, and when your brain
processes emotions and memories⁴⁷. When sleep apnea wakes you
repeatedly, you miss these restorative sleep stages. Disturbed sleep can
leave you feeling emotionally
drained and more vulnerable to anxiety and depression.

Untreated sleep apnea can also trigger inflammation throughout the
body. Research has linked chronic inflammation to mood
problems.⁸ Stress hormones, particularly cortisol, also rise
when you don’t get adequate sleep.⁹ Elevated cortisol levels
can intensify anxiety, making it harder to feel calm during the
day.¹⁰

Your body runs on an internal clock called a circadian rhythm, which
regulates when you feel alert or sleepy. This rhythm also influences
hormone production, body temperature and mood.¹¹ When sleep
apnea repeatedly disrupts your sleep, it throws these rhythms off,
affecting how you feel emotionally and how well you handle stress.

Telling the difference: sleep apnea vs. mental health conditions

Sleep apnea and mental health conditions share many symptoms, making
diagnosis more complex. Both conditions can cause mood changes and leave
you feeling tired, irritable, and unable to concentrate.⁴⁸
This overlap means people may receive treatment for depression or
anxiety when the root cause could be untreated sleep apnea. In some
cases, a person may be living with both sleep apnea and a mental health
condition, making diagnosis even harder.

Symptoms that suggest sleep apnea would be frequent snoring (that
keeps you or your loved one up) or pauses in breath during sleep
(usually noticed by a bed partner). Signs that point more toward anxiety
may include persistent worry, and excessive fear that interferes with
daily life.² Depression symptoms can include persistent
sadness, loss of interest in activities you once enjoyed, feelings of
hopelessness and sometimes thoughts of self-harm.³

However, sleep apnea, depression, and anxiety can overlap, so it’s
easy to mix them up. They may share symptoms like:

• Daytime tiredness or low energy
• Trouble sleeping or staying asleep
• Irritability or feeling on edge
• Trouble focusing or “brain fog”
• Morning headaches
• Low motivation or less interest in usual activities
• Restlessness or feeling keyed up
• Mood changes like sadness, worry or frustration

How sleep apnea contributes to anxiety and depression

The link with anxiety

Sleep apnea can mirror anxiety symptoms. For example, a person with
sleep apnea may wake up with a racing heart, gasping for air, which can
feel similar to a panic attack.¹⁴

For some people, these physical sensations may contribute to feelings
of anxiety or panic, creating a connection between their sleep disorder
and anxiety symptoms. Even if you don’t fully wake up, your body may
register these breathing pauses as threats, activating your “fight or
flight” stress response.⁴⁹ Plus, ongoing sleep deprivation
can make your brain more reactive to stress.⁶

The link with depression

Deep sleep helps with emotional recovery by allowing your brain to
process the day’s experiences, consolidate memories and restore
emotional balance.¹⁵ When sleep apnea prevents you from
reaching or maintaining deep sleep, it can be harder to bounce back from
emotional challenges.

Chronic fatigue from untreated sleep apnea leads some people to
withdraw from daily activities.¹⁶ When you’re constantly
exhausted, socializing may feel like too much effort, hobbies might lose
their appeal and even completing basic household tasks can seem
overwhelming. This withdrawal can deepen feelings of isolation and
depression.

The brain fog and difficulty concentrating that may come with sleep
apnea can affect your performance.¹⁷ When you can’t think
clearly or remember things, it can make tasks you previously didn’t find
difficult challenging. You might feel less capable at work or in
personal relationships, which can contribute to depressive thoughts.

Low oxygen levels during sleep affect serotonin and dopamine, brain
chemicals that play essential roles in mood regulation.^6,46
People who sleep six or fewer hours per night are 2.5 times more likely
to suffer frequent mental distress,¹⁸ and constant tiredness
may contribute to feelings of hopelessness and reduced quality of
life.^16,19

Who is most at risk?

Anxiety and depression tend to affect women more.^50,51
Women with sleep apnea also tend to have nonspecific symptoms such as
insomnia, depression, fatigue, morning headaches and nightmares, which
may contribute to lower rates of diagnosis and treatment compared to
men.²⁰

Older adults with untreated sleep apnea may be misdiagnosed with
dementia.²¹ The cognitive impairment and mood changes that
can accompany severe sleep deprivation may look similar to those sleep
apnea, leading to the wrong treatment approach.

Veterans and other individuals living with post-traumatic stress
disorder (PTSD) face higher rates of both sleep apnea and mental health
struggles. The nightmares, hypervigilance, and sleep disruption
associated with PTSD may overlap with sleep apnea symptoms, making them
worse. Additionally, the breathing pauses and oxygen drops from sleep
apnea may be associated with more intense PTSD symptoms. Studies
estimate that 67% to 69% of the veterans who have PTSD²² also
have sleep-disordered breathing.

People with excess weight or obesity may experience a challenging
cycle where weight gain contributes to sleep apnea, and sleep apnea
makes it harder to maintain a healthy weight.²³ Both
conditions can contribute to depression.

Individuals with treatment-resistant depression, meaning depression
that doesn’t improve with standard antidepressant medications, may have
undiagnosed sleep apnea.²⁴ When depression treatments aren’t
working, screening for and treating sleep disorders could be useful.

Why severity and getting treatment matter

Sleep apnea severity is measured by the apnea-hypopnea index (AHI),
which counts how many times per hour your breathing stops or becomes
very shallow during sleep. An AHI score of 5–14 indicates mild sleep
apnea, 15–30 indicates moderate sleep apnea, and an AHI of more than 30
indicates severe sleep apnea.²⁵

Studies shown that people with more severe sleep apnea tend to report
more depressive symptoms, with severe sleep apnea being associated with
a higher risk of depression.²⁶ Research also shows a
correlation between sleep apnea severity and the frequency of anxiety,
with more frequent breathing pauses during the night being associated
with higher levels of anxiety during the day.²⁷

Greater drops in oxygen levels during sleep can lead to greater
strain on the body and brain. Lower levels of oxygen in the blood have
been linked to morning depression — a heavy, sad feeling when you first
wake up.²⁸ The longer your sleep apnea goes untreated, the
greater the mental health risks become.

Treatment approaches and outcomes

CPAP therapy and mental health

Continuous positive airway pressure (CPAP) therapy
uses gentle air pressure to keep your airways open while you sleep.
Research on CPAP treatment and depression or anxiety has shown
encouraging results. One study demonstrated that less
than 9 of the 213 people living with sleep apnea who had depressive
symptoms still had symptoms after 3 months of consistent CPAP
therapy.²⁹ Another study showed a decrease in anxiety after 6
months of using a CPAP
device consistently, with further improvement after 1
year.³⁰

Research using brain imaging has shown CPAP therapy to help restore
brain patterns that control mood and emotions.^{31, 32} In
short, treating sleep apnea may help the brain manage feelings and
emotions better.

Treating sleep apnea and mental health conditions together

Combining CPAP therapy with cognitive behavioral therapy for insomnia
(CBT-I) can be helpful when sleep apnea and mental health conditions
coexist. ⁵³ CBT-I is a structured program that can help
people identify and change thoughts and behaviors interfering with
sleep. It teaches techniques for falling asleep, staying asleep and
developing healthier sleep habits.

CBT-I may also help with comorbid insomnia and sleep apnea (COMISA),
which is when someone is living with both insomnia and sleep apnea. In
one study, participants using CBT-I who used their CPAP each night
showed greater improvement in the severity of their
insomnia.³³

Other treatment options may include prescription medications to
address a mental health condition. However, consult a doctor before
taking antidepressant medications, due to various potential side
effects.³⁴

Mindfulness and relaxation techniques may help reduce stress and
improve sleep quality.³⁶ Deep breathing, meditation or
progressive muscle relaxation can calm your nervous system, making it
easier to fall asleep and reduce anxiety symptoms.

Collaboration between sleep specialists and mental health providers
may lead to better results. By sharing information, they can create a
comprehensive treatment plan that addresses all aspects of your health
rather than treating each condition separately.

Long-term care and monitoring

Mental health symptoms should be checked regularly throughout sleep
apnea treatment.^{37, 38} Continue talking about your sleep
quality and emotional well-being with your healthcare providers. Some
people may experience significant mood improvements immediately, while
others may need to adjust their treatment plan or request additional
mental health support.

Lifestyle changes can improve sleep and mental health. Examples
include:

• Maintaining good sleep habits, like keeping a consistent bedtime,
  creating a comfortable sleep environment and limiting screens before
  bed.
• Getting regular exercise, which may help improve mood, sleep
  quality and physical health.
• Using stress management techniques, such as physical activity or
  creating routines, to help you cope with daily challenges without
  becoming overwhelmed.

Support groups provide opportunities to learn tips and strategies
from people with similar experiences. Plus, connecting with others who
understand the challenges of sleep apnea or managing mental health
conditions can reduce feelings of isolation.

Even with continuous positive airway pressure (CPAP) therapy,
monitoring lingering sleep problems is important.¹⁵

Talking to your doctor about mental health and sleep

Several barriers may prevent people from seeking treatment for sleep
apnea and mental health conditions, including:

• Stigma about sleep disorders and mental health,
  which can delay getting help.^{39, 40}
• Insurance coverage may not include all testing
  or therapy options.
• Lack of awareness among doctors who may not
  recognize the mental health connection to sleep apnea.

Tips for having a conversation with your doctor about sleep and
mental health include:

• Tracking your symptoms ahead of time can help your doctor fully
  understand your experience.
• Making a list of medications and supplements you’re taking, so
  your doctor knows what might impact your sleep and treatment.
• Asking questions about anything you don’t understand, including
  what tests might be recommended and how treatments work.
• Being honest about your symptoms so your doctor can make informed
  decisions.

To learn more about your sleep health, take our online Sleep assessment.

This article is for educational purposes only. Certain treatment options discussed in this article, such as CPAP, require a prescription. Consult your doctor for medical advice.

References:

1. Source: Resmed’s 2025 Global Sleep Survey. https://sleepsurvey.resmed.com/
2. Source: Anxiety Disorders. National Institute of Mental Health (NIMH). https://www.nimh.nih.gov/health/publications/generalized-anxiety-disorder-gad
3. Source: Depression. National Institute of Mental Health (NIMH). https://www.nimh.nih.gov/health/publications/depression
4. Source: National Library of Medicine, Behavioral Sleep Medicine. Association of anxiety and depression in obstructive sleep apnea patients. https://pubmed.ncbi.nlm.nih.gov/30453780/
5. Source: National Library of Medicine, Journal of the Tunisian Society of Medical Sciences. Prevalence of depression and anxiety in obstructive sleep apnea. https://pmc.ncbi.nlm.nih.gov/articles/PMC9703910/
6. Source: Palo Alto University. Silent disruptor: Sleep apnea’s secret impact on mental health. https://paloaltou.edu/resources/business-of-practice-blog/silent-disruptor-sleep-apnea-impact-on-mental-health
7. Source: American Heart Association, STROKE. Impact of sleep disorders and disturbed sleep on brain health. https://www.ahajournals.org/doi/10.1161/STR.0000000000000453
8. Source: International Journal of Molecular Sciences. Obstructive sleep apnea and inflammation: Proof of concept based on two illustrative cytokines. https://www.mdpi.com/1422-0067/20/3/459
9. Source: National Library of Medicine, Sleep Science. Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. https://pmc.ncbi.nlm.nih.gov/articles/PMC4688585/
10. Source: National Library of Medicine. Effect of increase in cortisol level due to stress in healthy young individuals on dynamic and static balance scores. https://pmc.ncbi.nlm.nih.gov/articles/PMC6371989/
11. Source: National Library of Medicine, StatPearls. Physiology, Circadian rhythm. https://www.ncbi.nlm.nih.gov/books/NBK519507/
12. Source: UC Davis Health. Symptoms of anxiety and how to know when you need help. https://health.ucdavis.edu/blog/cultivating-health/symptoms-of-anxiety-and-how-to-know-when-you-need-help/2024/08
13. Source: National Institute of Mental Health. Depression. https://www.nimh.nih.gov/health/publications/depression
14. Source: National Library of Medicine, Annals of Family Medicine. Sleep apnea and risk of panic disorder. https://pmc.ncbi.nlm.nih.gov/articles/PMC4508172/
15. Source: National Library of Medicine, Psychological Bulletin. Overnight therapy? The role of sleep in emotional brain processing. https://pmc.ncbi.nlm.nih.gov/articles/PMC2890316/
16. Source: National Library of Medicine, Health and Quality of Life Outcomes. Fatigue is distinct from sleepiness and negatively impacts individuals living with obstructive sleep apnea (OSA): results from qualitative research of individuals with OSA. https://pmc.ncbi.nlm.nih.gov/articles/PMC11934705/
17. Source: National Library of Medicine, Frontiers in Psychology. Cognitive impairment and affective disorders in patients with obstructive sleep apnea syndrome. https://pmc.ncbi.nlm.nih.gov/articles/PMC6091233/
18. Source: Centers for Disease Control and Prevention, Preventing Chronic Disease. Effect of inadequate sleep on frequent mental distress. https://www.cdc.gov/pcd/issues/2021/20_0573.htm
19. Source: Science Direct, Sleep Medicine. Clinical depression in untreated obstructive sleep apnea: examining predictors and a meta-analysis of prevalence rates. https://www.sciencedirect.com/science/article/abs/pii/S138994571930070X
20. Source: Karger, Medical Principles and Practice. Evaluation of obstructive sleep apnea in female patients in primary care: time for improvement? https://karger.com/mpp/article/30/6/508/825034/Evaluation-of-Obstructive-Sleep-Apnea-in-Female
21. Source: National Library of Medicine, GeroScience. Intricate relationship between obstructive sleep apnea and dementia in older adults. https://pmc.ncbi.nlm.nih.gov/articles/PMC10828345/
22. Source: National Library of Medicine, Brain Sciences. Sleep and PTSD in the military forces: a reciprocal relationship and a psychiatric approach. https://pmc.ncbi.nlm.nih.gov/articles/PMC8533994/
23. Source: National Library of Medicine, CHEST. Interactions between obesity and obstructive sleep apnea. https://pmc.ncbi.nlm.nih.gov/articles/PMC3021364/
24. Source: National Library of Medicine, Journal of Psychiatric Research. Prevalence of obstructive sleep apnea in suicidal patients with major depressive disorder. https://pmc.ncbi.nlm.nih.gov/articles/PMC6606377/
25. Source: National Library of Medicine, Annals of Medical and Health Sciences Research. Obstructive sleep apnea hypopnea syndrome. https://pmc.ncbi.nlm.nih.gov/articles/PMC3507119/
26. Source: BMC Public Health. Association of sleep apnea and depressive symptoms among US adults. https://bmcpublichealth.biomedcentral.com/articles/10.1186/s12889-023-15358-8
27. Source: National Library of Medicine, Journal of Research in Medical Sciences. The correlation of anxiety and depression with obstructive sleep apnea syndrome. https://pubmed.ncbi.nlm.nih.gov/24949026/
28. Source: Wiley Online Library, Journal of Sleep Research. Waking up on the wrong side of the bed: depression severity moderates daily associations between sleep duration and morning affect. https://onlinelibrary.wiley.com/doi/10.1111/jsr.14010
29. Source: American Academy of Sleep Medicine. CPAP therapy reduces symptoms of depression in adults with sleep apnea. https://aasm.org/cpap-therapy-reduces-symptoms-of-depression-in-adults-with-sleep-apnea/
30. Source: National Library of Medicine, Medicina. CPAP Therapy on depressive and anxiety symptoms in patients with moderate to severe obstructive sleep apnea syndrome. https://pmc.ncbi.nlm.nih.gov/articles/PMC9609270/
31. Source: National Library of Medicine, American Journal of Respiratory and Critical Care Medicine. Obstructive sleep apnea: brain structural changes and neurocognitive function before and after treatment. https://pubmed.ncbi.nlm.nih.gov/21037021/
32. Source: National Library of Medicine, Journal of Neuroscience Research. Altered global and regional brain mean diffusivity in patients with obstructive sleep apnea. https://pubmed.ncbi.nlm.nih.gov/22715089/
33. Source: National Library of Medicine, Sleep. Cognitive and behavioral therapy for insomnia increases the use of continuous positive airway pressure therapy in obstructive sleep apnea participants with comorbid insomnia. https://pubmed.ncbi.nlm.nih.gov/31403168/
34. Source: National Library of Medicine, Current Psychiatry Reports. Effects of antidepressants on sleep. https://pmc.ncbi.nlm.nih.gov/articles/PMC5548844/
35. Source: Science Daily, Endocrine Society. Sleep, mood improves after substantial weight loss. https://www.sciencedaily.com/releases/2014/06/140624135755.htm
36. Source: National Library of Medicine, Annals of the New York Academy of Sciences. The effect of mindfulness meditation on sleep quality. https://pmc.ncbi.nlm.nih.gov/articles/PMC6557693/
37. Source: National Library of Medicine, Sleep Health. Sleep apnea, psychopathology, and mental health care. https://pmc.ncbi.nlm.nih.gov/articles/PMC5560422/
38. Source: Science Direct, Sleep Medicine Reviews. Persistent sleepiness in CPAP treated obstructive sleep apnea patients: evaluation and treatment. https://www.sciencedirect.com/science/article/abs/pii/S108707920700038X
39. Source: National Library of Medicine, Cureus. Understanding and addressing mental health stigma across cultures for improving psychiatric care. https://pmc.ncbi.nlm.nih.gov/articles/PMC10220277/
40. Source: National Institutes of Health. Sleep disorders and sleep deprivation: an unmet public health problem. https://www.ncbi.nlm.nih.gov/books/NBK19963/
41. Source: Jehan S, Auguste E, Pandi-Perumal SR, et al. Depression, obstructive sleep apnea and psychosocial health. Sleep Med Dis Int J. 2017;1(3):58–63. doi:10.15406/smdij.2017.01.00012. https://pmc.ncbi.nlm.nih.gov/articles/PMC5836734/
42. Source: Gupta MA, Simpson FC. Obstructive sleep apnea and psychiatric disorders: a systematic review. J Clin Sleep Med. 2015;11(2):165–175. doi:10.5664/jcsm.4466. https://pmc.ncbi.nlm.nih.gov/articles/PMC4298774/
43. Source: Zhao DF, Zhang YZ, Sun X, Su CY, Zhang LQ. Association between obstructive sleep apnea severity and depression risk: a systematic review and dose-response meta-analysis. Sleep Breath. 2024;28(5):2175–2185. doi:10.1007/s11325-024-03019-2. https://pubmed.ncbi.nlm.nih.gov/38888794/
44. Source: Lundetræ RS, Saxvig IW, Lehmann S, Bjorvatn B. Effect of continuous positive airway pressure on symptoms of anxiety and depression in patients with obstructive sleep apnea. Sleep Breath. 2021;25(3):1277–1283. doi:10.1007/s11325-020-02234-7. https://pubmed.ncbi.nlm.nih.gov/33098538/
45. Source: Slowik JM, Sankari A, Collen JF. Obstructive sleep apnea. [Updated 2025 Mar 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. https://www.ncbi.nlm.nih.gov/books/NBK459252/
46. Source: Teleanu DM, Niculescu AG, Roza E, Vladacenco O, Grumezescu AM, Teleanu RI. Neurotransmitters—key factors in neurological and neurodegenerative disorders of the central nervous system. Int J Mol Sci. 2022;23(11):5954. doi:10.3390/ijms23115954. https://pmc.ncbi.nlm.nih.gov/articles/PMC9180936/
47. Source: Patel AK, Reddy V, Shumway KR, Araujo JF. Physiology, sleep stages. [Updated 2024 Jan 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2026. https://www.ncbi.nlm.nih.gov/books/NBK526132/
48. Source: Kerner NA, Roose SP. Obstructive sleep apnea is linked to depression and cognitive impairment: evidence and potential mechanisms. Am J Geriatr Psychiatry. 2016;24(6):496–508. doi:10.1016/j.jagp.2016.01.134. https://pmc.ncbi.nlm.nih.gov/articles/PMC5381386/
49. Source: Sleep Medicine. 2021. doi:10.1016/j.sleep.2021.11.012. https://www.sciencedirect.com/science/article/abs/pii/S1389945721004810
50. Source: Why is depression more prevalent in women? J Psychiatry Neurosci. 2015;40(4):219–221. doi:10.1503/jpn.150205. https://pmc.ncbi.nlm.nih.gov/articles/PMC4478054/
51. Source: McLean CP, Asnaani A, Litz BT, Hofmann SG. Gender differences in anxiety disorders: prevalence, course of illness, comorbidity and burden of illness. J Psychiatr Res. 2011;45(8):1027–1035. doi:10.1016/j.jpsychires.2011.03.006. https://pmc.ncbi.nlm.nih.gov/articles/PMC3135672/
52. Source: Gender differences in obstructive sleep apnea and treatment. Sleep Med Rev. 2008;12(6):481–496. doi:10.1016/j.smrv.2007.11.003. https://pmc.ncbi.nlm.nih.gov/articles/PMC2642982/
53. Source: Sweetman A, Lack L, McEvoy RD, et al. Effect of depression, anxiety, and stress symptoms on response to cognitive behavioral therapy for insomnia in patients with comorbid insomnia and sleep apnea: a randomized controlled trial. J Clin Sleep Med. 2021;17(3):545–554. doi:10.5664/jcsm.8944. https://pmc.ncbi.nlm.nih.gov/articles/PMC7927315/
54. Source: Hirotsu C, Tufik S, Andersen ML. Interactions between sleep, stress, and metabolism: from physiological to pathological conditions. Sleep Sci. 2015;8(3):143–152. doi:10.1016/j.slsci.2015.09.002. https://pmc.ncbi.nlm.nih.gov/articles/PMC4688585/