Non 24 Hour Sleep Wake Syndrome
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Transcript of Non 24 Hour Sleep Wake Syndrome
Non-24-Hour Sleep-Wake Syndrome
Ina Keyser10144383
FLG 327
University of Pretoria17 October 2012
Figure 1: Woman Sleeping
Non-24-Hour Sleep-Wake Syndrome
Also known as: free-running type circadian arrhythmia
DEF: Chronic sleeping disorder
Normal Physiology
Circadian Rhythms Latin origin: circa means “around” and diem
means “day”
Biological process that displays an endogenous, entrained oscillation of 24 hours
Self-sustained and adjust to the local environment by external cues (zeitgebers)
Important zeitgeber = daylight
Normal Physiology CONTINUED
Suprachiasmic nucleus (SCN) is a group of cells located in the hypothalamus
Receives information through illimination of the eyes
Retina contain photosensitive ganglion cells which contains melanopsin
Signals follow a pathway, known as the retinohypothalamic tract to SCN Figure 2: Sagittal Section of Brain
Normal Physiology CONTINUED
SCN takes the information, interprets it and passes it on to the pineal gland (epithalamus)
Pineal gland secretes melatonin
Melatonin peaks at night and ebbs during the day
Figure 2: Sagittal Section of Brain
Normal Physiology CONTINUED
“Internal biological clock” or circadian rhythm adheres to a 24 hour cycle
Daily variances are caused by environmental factors: physical or emotional stress
These variances even out and stabilises again to a 24 hour cycle
No harmful effects to the body
Non-24-Hour Sleep-Wake Syndrome No internal clocks that resets balances within a 24
hour schedule Body insists that the day is longer than 24 hours
Circadian rhythm function over longer periods of time
e.g. 72 hour cycles: stay awake for 48 straight hours and then sleep for 24 straight hours as a regular sleeping pattern
Most cases fall within a 25 to 27 hour range.
Non-24-Hour Sleep-Wake Syndrome CONTINUED
N24 makes it impossible for the individual to sleep at normal (socially accepted) times
Untreated N24 causes a person's sleep-wake cycle to change every day
Degree related to how much over 24 hours the cycle lasts
The cycle progresses around the clock, eventually returning to "normal" for one or two days before "going off" again
Figure 3: Woman Awake
Prevalence Most cases reported in medical literature occurred in blind individuals
50% of completely blind individuals present with N24
Circadian arrhythmia can occur at any age, from birth onwards
Generally follows shortly after loss or removal of the individual’s eyes or damage to the retina
The first detailed study of N24 was made on a blind subject
28-year-old male presented with a 24.9-hour sleep cycle (as well as plasma cortisol and other parameters).
Even while adhering to a 24-hour schedule for bedtime, rise time, work and meals; the man’s body rhythms continued to shift.
Rare among visually impaired individuals (maintain some light perception)
Research suggest, low light exposure can synchronize the body clock
Prevalence CONTINUED
N24 have been reported in sighted individuals
BUT very rare and the etiology is less well understood in these cases
Since 2005, less than 140 cases reported
• cranial injury• pituitary adenoma removed (involving the optic chiasma)
N24 is thought to involve abnormal functioning of the SCN abnormal secretions of melatonin
Thus neurological in origin
Figure 4: Pituitary Adenoma
Signs and SymptomsDifficulty in adjusting to changes in "regular" sleep-wake cycles, due to:
• stress• evening activities• travel to different time zones• vacations• illness and use of medications (especially stimulants or sedatives)• changes in daylight hours in different seasons• time changes e.g. daylight savings time• growth spurts (which cause fatigue)
Commonly impairs their ability to function socially and occupationally
Characteristically, they are "partially or totally unable to function in scheduled activities on a daily basis, and most are unable to work at conventional jobs" [1]
Attempts to keep to the social and conventional hours, patients may develop insomnia (not a normal symptom of N24) and excessive sleepiness during the day
Figure 5: Girl in Class
Signs and Symptoms CONTINUED
Side-effects associated with acute and chronic sleep deprivation:
• Cognitive dysfunction• Confusion• Diarrhoea• Extreme nausea• Extreme fatigue• Hair loss• Headaches Figure 6: Man Sleeping at
Work
Diagnosis and PrognosisDiagnosis: History of your past sleeping routines Medical history Recent changes in your lifestyle Drug or medication use Neurological test e.g. ECG Body temperature and melatonin levels
Prognosis: Attempt to reset and balance your circadian rhythm
Fixed schedule at set times no matter when you wake up
Melatonin hormone therapy is the most widely used treatment Chronotherapy and acupuncture
References1. Bretzl, H. (1903). Botanische Forschungen des Alexanderzuges. Leipzig: Teubner. [page needed
2. Gwei-Djen Lu (25 October 2002). Celestial Lancets. Psychology Press. pp. 137–140. ISBN 978-0-7007-1458-2.
3. ^ de Mairan JJO (1729). "Observation Botanique". Histoire de l'Academie Royale des Sciences: 35–36.
4. ^ Gardner MJ, Hubbard KE, Hotta CT, Dodd AN, Webb AA (July 2006). "How plants tell the time". The Biochemical Journal 397 (1): 15–24. doi:10.1042/BJ20060484. PMC 1479754. PMID 16761955. http://www.biochemj.org/bj/397/0015/bj3970015.htm. Retrieved 2010-06-11.
5. ^ Dijk, Derk-Jan; Malcolm von Schantz (August 2005). "Timing and Consolidation of Human Sleep, Wakefulness, and Performance by a Symphony of Oscillators". J Biol Rhythms (SagePub) 20 (4): 279–290. doi:10.1177/0748730405278292. PMID 16077148. http://jbr.sagepub.com/content/20/4/279.full.pdf+html. Retrieved 2010-10-14.
6. ^ Danchin, Antoine. "Important dates 1900–1919". HKU-Pasteur Research Centre (Paris). http://www.pasteur.fr/recherche/unites/REG/causeries/dates_1900.html. Retrieved 2008-01-12.
7. ^ Konopka R, Benzer S (September 1971). "Clock Mutants of Drosophila melanogaster". Proc. Nat. Acad. Sci. USA 68 (9): 2112–2116. Bibcode 1971PNAS...68.2112K. doi:10.1073/pnas.68.9.2112. PMC 389363. PMID 5002428. //www.ncbi.nlm.nih.gov/pmc/articles/PMC389363/.
8. "Gene Discovered in Mice that Regulates Biological Clock". Chicago Tribune. 29 April 1994.