Editing Somnolence

{{short description|State of desire for sleep, for unusually long periods}}
{{Infobox medical condition (new)
 |name          = Somnolence
 |synonym       = Sleepiness, drowsiness
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'''Somnolence''' (alternatively '''sleepiness''' or '''drowsiness''') is a state of strong desire for [[sleep]], or sleeping for unusually long periods (compare [[hypersomnia]]). It has distinct meanings and causes. It can refer to the usual state preceding [[Sleep onset|falling asleep]],<ref>{{cite journal |doi=10.1523/JNEUROSCI.2262-11.2011|url=https://zenodo.org/record/1065640|pmid=22131409|pmc=6623815|title=Getting Drowsy? Alert/Nonalert Transitions and Visual Thalamocortical Network Dynamics|journal=Journal of Neuroscience|volume=31|issue=48|pages=17480–7|year=2011|last1=Bereshpolova|first1=Y.|last2=Stoelzel|first2=C. R.|last3=Zhuang|first3=J.|last4=Amitai|first4=Y.|last5=Alonso|first5=J.-M.|last6=Swadlow|first6=H. A.}}</ref> the condition of being in a drowsy state due to [[circadian rhythm]] disorders, or a symptom of other health problems. It can be accompanied by [[lethargy]], weakness and lack of mental agility.<ref name=":0">{{Cite web|title = Drowsiness – Symptoms, Causes, Treatments|url = http://www.healthgrades.com/symptoms/drowsiness|website = www.healthgrades.com|date = 26 June 2014|access-date = 2015-10-31}}</ref>

Somnolence is often viewed as a symptom rather than a disorder by itself. However, the concept of somnolence recurring at certain times for certain reasons constitutes various disorders, such as [[excessive daytime sleepiness]], [[shift work sleep disorder]], and others; and there are [[medical classification|medical codes]] for somnolence as viewed as a disorder.

Sleepiness can be dangerous when performing tasks that require constant concentration, such as driving a vehicle. When a person is sufficiently [[fatigue]]d, [[microsleep]]s may be experienced. In individuals deprived of sleep, somnolence may spontaneously dissipate for short periods of time; this phenomenon is the [[second wind (sleep)|second wind]], and results from the normal cycling of the circadian rhythm interfering with the processes the body carries out to prepare itself to rest.

The word "somnolence" is derived from the [[Latin]] "somnus" meaning "sleep".

== Causes ==
[[File:Biological clock human.svg|thumb|340px|Some features of the human circadian (24-hour) biological clock. ''Click to enlarge'']]

=== Circadian rhythm disorders ===
{{Main|Circadian rhythm sleep disorder}}
Circadian rhythm ("biological clock") disorders are a common cause of drowsiness as are a number of other conditions such as sleep apnea, insomnia and narcolepsy.<ref name=":0"/> The body clock disorders are classified as extrinsic (externally caused) or intrinsic. The former type is, for example, shift work sleep disorder, which affects people who work nights or rotating shifts. The intrinsic types include:<ref>{{Cite web|title = Circadian Sleep Disorders Network|url = http://www.circadiansleepdisorders.org/|website = www.circadiansleepdisorders.org|access-date = 2015-11-02}}</ref>
* [[Advanced sleep phase disorder]] (ASPD) – A condition in which patients feel very sleepy and go to bed early in the evening and wake up very early in the morning
* [[Delayed sleep phase disorder]] (DSPD) – Faulty timing of sleep, peak period of alertness, the core body temperature rhythm, hormonal and other daily cycles such that they occur a number of hours late compared to the norm, often misdiagnosed as insomnia
* [[Non-24-hour sleep–wake disorder]] – A faulty body clock and sleep-wake cycle that usually is longer than (rarely shorter than) the normal 24-hour period causing complaints of insomnia and excessive sleepiness
* [[Irregular sleep–wake rhythm]] – Numerous naps throughout the 24-hour period, no main nighttime sleep episode and irregularity from day to day

=== Physical illness ===
Sleepiness can also be a response to infection.<ref>{{cite journal |first1=Janet |last1=Mullington |first2=Carsten |last2=Korth |first3=Dirk M. |last3=Hermann |first4=Armin |last4=Orth |first5=Chris |last5=Galanos |first6=Florian |last6=Holsboer |first7=Thomas |last7=Pollmächer |title=Dose-dependent effects of endotoxin on human sleep |journal=American Journal of Physiology. Regulatory, Integrative and Comparative Physiology |volume=278 |issue=4 |pages=R947–55 |year=2000 |pmid=10749783 |doi=10.1152/ajpregu.2000.278.4.r947|s2cid=10272455 }}</ref> Such somnolence is one of several [[sickness behavior]]s or reactions to infection that some theorize evolved to promote recovery by conserving energy while the body fights the infection using fever and other means.<ref name="Hart">{{cite journal |doi=10.1016/S0149-7634(88)80004-6|title=Biological basis of the behavior of sick animals|journal=Neuroscience & Biobehavioral Reviews|volume=12|issue=2|pages=123–37|year=1988|last1=Hart|first1=Benjamin L.|pmid=3050629|s2cid=17797005}}</ref><ref>{{cite journal |doi=10.1016/S0889-1591(02)00077-6|title=Cytokine-induced sickness behavior|journal=Brain, Behavior, and Immunity|volume=17|pages=112–118|year=2003|last1=Kelley|first1=Keith W.|last2=Bluthé|first2=Rose-Marie|last3=Dantzer|first3=Robert|last4=Zhou|first4=Jian-Hua|last5=Shen|first5=Wen-Hong|last6=Johnson|first6=Rodney W.|last7=Broussard|first7=Suzanne R.|pmid=12615196|issue=1|s2cid=25400611}}</ref> Other causes include:<ref>{{Cite web|title = Drowsiness: MedlinePlus Medical Encyclopedia|url = https://www.nlm.nih.gov/medlineplus/ency/article/003208.htm|website = www.nlm.nih.gov|access-date = 2015-10-31}}</ref>
* [[Anxiety]] 
* [[Brain tumor]]
* [[Chronic pain]]s
* [[Concussion]] – a mild traumatic brain injury 
* [[Diabetes]]
* [[Fibromyalgia]]
* [[Head injury]]
* [[Hypercalcemia]] – too much calcium in the blood
* [[Hypermagnesemia]]
* [[Hyponatremia]] – low blood sodium 
* [[Hypothyroidism]] – the body doesn't produce enough hormones that control how cells use energy
* [[Meningitis]]
* [[Mood disorder]]s – [[Depression (mood)|depression]]
* [[Multiple sclerosis]] 
* [[Narcolepsy]] – disorder of the nervous system
* [[Skull fracture]]s
* [[African trypanosomiasis|Sleeping sickness]] – caused by a specific parasite
* [[Stress (biology)|Stress]]

=== Medicine ===
{{more citations needed|section|date=November 2019}}

* [[Analgesic]]s – mostly prescribed or illicit [[opiate]]s such as [[OxyContin]] or [[heroin]]
* Anticonvulsants / [[antiepileptic]]s – such as [[phenytoin]] (Dilantin), [[carbamazepine]] (Tegretol), [[Pregabalin]] (Lyrica) and [[Gabapentin]] (Neurontin)
* [[Antidepressants]] – for instance, sedating [[tricyclic antidepressants]]<ref name="pmid16832696">{{cite journal |last1=Zimmermann |first1=C. |last2=Pfeiffer |first2=H. |title=Schlafstörungen bei Depression: Behandlungsmöglichkeiten |journal=Der Nervenarzt |date=January 2007 |volume=78 |issue=1 |pages=21–30 |doi=10.1007/s00115-006-2111-1 |pmid=16832696 |trans-title=Sleep Disorders in Depression: Treatment options |language=German}}</ref> [[amitriptyline]] and  [[mirtazapine]]. Somnolence is less common with [[SSRI]]s<ref name="pmid22161405">{{cite journal |last1=Watanabe |first1=Norio |last2=Omori |first2=Ichiro M |last3=Nakagawa |first3=Atsuo |last4=Cipriani |first4=Andrea |last5=Barbui |first5=Corrado |last6=Churchill |first6=Rachel |last7=Furukawa |first7=Toshi A |year=2011 |title=Mirtazapine versus other antidepressive agents for depression |journal=Cochrane Database of Systematic Reviews |issue=12 |pages=CD006528 |pmid=22161405 |pmc=4158430 |doi=10.1002/14651858.CD006528.pub2}}</ref> and [[SNRI]]s as well as [[MAOI]]s.
* [[Antihistamines]] – for instance, [[diphenhydramine]] ([[Benadryl]], [[Nytol]]), [[doxylamine]] (Unisom-2), [[hydroxyzine]] (Atarax) and [[promethazine]] (Phenergan)
* [[Antipsychotics]] – for example, [[Lurasidone]] (Latuda), [[thioridazine]], [[quetiapine]] (Seroquel), [[olanzapine]] (Zyprexa), [[risperidone]] and [[ziprasidone]] ([[Geodon]]) but not [[haloperidol]]
* [[Dopamine agonists]] used in the treatment of [[Parkinson's disease]] – e.g. [[pergolide]], ropinirole and [[pramipexole]].
* [[HIV]] medications – such as [[efavirenz]]
* [[Hypertension]] medications – such as [[amlodipine]]
* [[Hypnotic]]s, or soporific drugs, commonly known as sleeping pills.
* [[Tranquilizers]] – such as [[zopiclone]] (Zimovane), or the [[benzodiazepine]]s such as [[diazepam]] (Valium) or [[nitrazepam]] (Mogadon) and the [[barbiturate]]s, such as [[amobarbital]] (Amytal) or [[secobarbital]] (Seconal)
* Other agents impacting the [[central nervous system]] in sufficient or toxic doses

== Assessment ==
Quantifying sleepiness requires a careful assessment. The diagnosis depends on two factors, namely chronicity and reversibility. Chronicity signifies that the patient, unlike healthy people, experiences persistent sleepiness which does not pass. Reversibility stands for the fact that, even if the individual goes to sleep, the sleepiness may not be completely gone after waking up. The problem with the assessment is that patients may only report the consequences of sleepiness: loss of energy, fatigue, weariness, difficulty remembering or concentrating, etc. It is crucial to aim for objective measures to quantify the sleepiness. A good measurement tool is the ''multiple sleep latency test'' (MSLT). It assesses the sleep onset latency during the course of one day—often from 8:00 to 16:00.<ref>{{Cite journal|last1=Kushida|first1=Clete A.|last2=Sullivan|first2=Shannon S.|date=2008-10-01|title=Multiple Sleep Latency Test and Maintenance of Wakefulness Test|url=https://journal.chestnet.org/article/S0012-3692(08)60320-7/abstract|journal=Chest|language=en|volume=134|issue=4|pages=854–861|doi=10.1378/chest.08-0822|issn=0012-3692|pmid=18842919|url-access=subscription}}</ref> An average sleep onset latency of less than 5 minutes is an indication of pathological sleepiness.<ref>{{Citation |last1=Roehrs |first1=Timothy |title=Daytime Sleepiness and Alertness |date=2017 |work=Principles and Practice of Sleep Medicine |pages=39–48.e4 |publisher=Elsevier |doi=10.1016/b978-0-323-24288-2.00004-0 |isbn=9780323242882 |last2=Carskadon |first2=Mary A. |last3=Dement |first3=William C. |last4=Roth |first4=Thomas |author-link4=Thomas Roth (scientist)}}</ref>

== Severity ==
A number of diagnostic tests, including the [[Epworth Sleepiness Scale]], are available to help ascertain the seriousness and likely causes of abnormal somnolence.<ref>Carskadon, M.A.; Dement, W.C.; Mitler, M.M.; Roth, T.; Westbrook, P.R.; Keenan, S. Guidelines for the Multiple Sleep Latency Test (MSLT): a standard measure of sleepiness. Sleep 1986; 9:519–524</ref><ref>{{ cite journal | last=Johns | first=MW | title=Sensitivity and specificity of the multiple sleep latency test (MSLT), the maintenance of wakefulness test and the epworth sleepiness scale: failure of the MSLT as a gold standard | journal=Journal of Sleep Research |volume=9 |issue=1 |pages=5–11 | date=March 2000 | pmid=10733683 | doi=10.1046/j.1365-2869.2000.00177.x | doi-access=free }}</ref>

== See also ==
{{colbegin}}
* {{wiktionary inline|somnolence|drowsiness}}
* [[Chronic fatigue syndrome]]
* [[Decision fatigue]]
* [[Fibromyalgia]]
* [[Insomnia]]
* [[Hypersomnia]]
* [[Dyssomnia]]
* [[Fatigue]]
* [[Narcolepsy]]
* [[Postprandial somnolence]]
* [[Restless legs syndrome]]
* [[Periodic limb movement disorder]]
* [[Hypnopompic]]
* [[Hypnagogia]]
*[[Sleep apnea]]
{{colend}}

== References ==
{{Reflist|2}}

==External links==
{{Medical resources
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| ICD9            = {{ICD9|780.09}}
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| MedlinePlus     = 003208
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{{Disorders of consciousness}}
{{SleepSeries2}}

[[Category:Symptoms and signs of mental disorders]]
[[Category:Sleep]]
[[Category:Mental processes]]

[[fr:Sommeil#Somnolence]]