Editing Sleep inertia (section)

==Causes==

Studies have shown that abrupt awakening during stage 3 sleep, [[slow-wave sleep]] (SWS), produces more sleep inertia than awakening during sleep stages 1, 2 or [[Rapid eye movement sleep|REM]] sleep.<ref name=":0">{{cite web|url=https://www.researchgate.net/publication/12367344|title=The sleep inertia phenomenon during the sleep-wake transition: Theoretical and operational issues (PDF Download Available)|website=ResearchGate|language=en|access-date=2017-05-02}}</ref> Prior sleep deprivation increases the percentage of time spent in slow-wave sleep (SWS). Therefore, an individual who was previously sleep deprived will have a greater chance of experiencing sleep inertia.<ref name=":1" /><ref name=":0" /> [[Adenosine]] levels in the brain progressively increase with sleep deprivation, and return to normal during sleep.  Upon awakening with sleep deprivation, high amounts of adenosine will be bound to receptors in the brain, neural activity slows down, and a feeling of tiredness will result.<ref>{{cite journal|last1=Newman|first1=Rachel A.|last2=Kamimori|first2=Gary H.|last3=Wesensten|first3=Nancy J.|last4=Picchioni|first4=Dante|last5=Balkin|first5=Thomas J.|title=Caffeine Gum Minimizes Sleep Inertia|journal=Perceptual and Motor Skills|language=en|volume=116|issue=1|pages=280–293|doi=10.2466/29.22.25.pms.116.1.280-293|pmid=23829154|year=2013|s2cid=808008}}</ref> Individuals express a lack of blood flow to the brain upon awakening. Levels of [[Cerebral circulation|cerebral blood flow]] (CBF) and cerebral blood flow velocities (CBFV) will take up to 30 minutes to increase and reach daytime levels.<ref name=":0" />  Cerebral blood flow returns to waking levels in the brainstem and thalamus first. After 15 minutes, the brain's anterior cortical regions receive normal daytime blood flow. This 15 minute time period corresponds to the sleep inertia period.{{cn|date=September 2022}} Additionally, alcoholic beverages in the evening can cause [[Hangover|physiological distress]] upon wake up.<ref>{{cite web|title=Hangovers {{!}} National Institute on Alcohol Abuse and Alcoholism (NIAAA)|url=https://www.niaaa.nih.gov/publications/brochures-and-fact-sheets/hangovers|access-date=2021-11-26|website=www.niaaa.nih.gov}}</ref><ref>{{cite web|title=Hangovers - Symptoms and causes|url=https://www.mayoclinic.org/diseases-conditions/hangovers/symptoms-causes/syc-20373012|access-date=2021-11-26|website=Mayo Clinic|language=en}}</ref>