Sleep | Medical Science Optional Notes for UPSC PDF Download

Definition

Sleep is the inherent recurring condition of repose for the mind and body, marked by closed eyes and featuring a state of partial or complete unconsciousness.

Mechanism/Neurophysiology of Sleep:
Sleep is induced by stimulating sleep centers, leading to activation.

Sleep | Medical Science Optional Notes for UPSC

Flip-Flop Switch

The ascending arousal system and the sleep-promoting system, two crucial neural networks, operate collaboratively with mutual inhibition, creating a neural circuit comparable to what electrical engineers term a "flip-flop switch." Such a switch facilitates swift transitions between the on (wake) and off (sleep) states, avoiding intermediate states. Numerous sleep-promoting neurons experience inhibition from inputs originating in the arousal system.

Sleep | Medical Science Optional Notes for UPSC

Sleep | Medical Science Optional Notes for UPSC

Neurons located in the ventrolateral preoptic nucleus, a crucial site for promoting sleep, diminish in number as part of the natural aging process in humans. This reduction in neurons correlates with a diminished capacity to sustain sleep, leading to sleep fragmentation. Furthermore, in Alzheimer's disease, these ventrolateral preoptic neurons are affected, potentially contributing to the compromised sleep quality observed in individuals with this condition.

Question for Sleep
Try yourself:
What is the mechanism of sleep?
View Solution

Rem Sleep Switch

The shift between NREM and REM sleep seems to be regulated by a comparable switch located in the brainstem. The switch governing REM sleep receives cholinergic input, promoting transitions into REM sleep, while it also receives monoaminergic input, specifically from norepinephrine and serotonin, which inhibits REM sleep.

Sleep | Medical Science Optional Notes for UPSC

Inhibition

The wakefulness-promoting function of the Ascending Reticular Activating System (ARAS) arises from its connections with the cerebral cortex, both afferently and efferently. Sleep is induced by inhibiting the ARAS.

Physiological Changes During Sleep

Sleep | Medical Science Optional Notes for UPSC

Stages/Types of sleep

Sleep | Medical Science Optional Notes for UPSC

The widely accepted average duration for an adult male's sleep cycle is 90 minutes, defined as extending from the conclusion of one REM period to the conclusion of the subsequent one. A typical 7-8-hour sleep likely encompasses five cycles, with the central two cycles having a propensity for longer durations, and REM occupying an increasing portion of the cycle as the night progresses.

N1 (NREM stage 1) denotes the transitional phase from drowsiness or wakefulness to falling asleep. In this stage, both brain waves and muscle activity begin to decrease.

N2 marks a phase of light sleep where eye movement has ceased. There is a reduction in brain wave frequency and muscle tonus, accompanied by a decrease in heart rate and body temperature.

N3 or N4 are the more challenging stages to rouse from. In these stages, the entire body enters a state of relaxation, characterized by decreased breathing, lowered blood pressure, and a reduction in body temperature.

Question for Sleep
Try yourself:
Which stage of sleep is characterized by a decrease in brain wave frequency, muscle tonus, heart rate, and body temperature?
View Solution

Variations of sleep cycle with age

The need for sleep is not consistent, but the average daily sleep requirement varies across different age groups:

  1. Newborn infants: 18 to 20 hours
  2. Growing children: 12 to 14 hours
  3. Adults: 7 to 9 hours
  4. Older individuals: 5 to 7 hours.

In infants, the sleep cycle typically lasts about 50-60 minutes, and its average duration increases as individuals progress into adulthood. In adults, sleep initiation involves NREM, while in infants, it commences with REM. REM-onset sleep is also observed in adults under conditions of jet lag or chronic sleep deprivation.

Sleep | Medical Science Optional Notes for UPSC

Sleep | Medical Science Optional Notes for UPSC

The sequence of EEG waves can be remembered as "Gay BAT Dance," representing the progression from gamma, beta, alpha, theta to delta frequencies, with a decrease in frequency and an increase in amplitude.

Normal Adult Brain Waves

Sleep | Medical Science Optional Notes for UPSC

Stages of sleep with EEG patterns

Sleep | Medical Science Optional Notes for UPSC

Question for Sleep
Try yourself:
What is the average daily sleep requirement for older individuals?
View Solution

Sleep Disorders

Narcolepsy is frequently linked with excessive daytime sleepiness and may manifest with:

  • Cataplexy - the sudden loss of muscle tone and paralysis of voluntary muscles.
  • Hypnagogic hallucinations - dreams occurring during the pre-sleep stage.
  • Automatic behaviors - engaging in activities automatically and having no recollection afterward.

Sleep | Medical Science Optional Notes for UPSC

Sleep and Consciousne -Repeats

  • Explore the neurophysiological foundation of sleep. (2016)
  • Provide a definition of sleep and delve into the various types of sleep. Examine the distinctions in the sleep patterns of a newborn in comparison to an adult. Additionally, discuss the electroencephalographic record's waveform during deep sleep. (2014)
  • Define sleep and offer a concise overview of the architecture of a sleep cycle. Examine how these patterns vary with age. (2010)
  • Analyze the physiology of normal sleep. (2007)
  • Define consciousness and identify the key brain regions responsible for it. Explore disturbances in consciousness. (2009)
The document Sleep | Medical Science Optional Notes for UPSC is a part of the UPSC Course Medical Science Optional Notes for UPSC.
All you need of UPSC at this link: UPSC
7 videos|219 docs

Top Courses for UPSC

7 videos|219 docs
Download as PDF
Explore Courses for UPSC exam

Top Courses for UPSC

Signup for Free!
Signup to see your scores go up within 7 days! Learn & Practice with 1000+ FREE Notes, Videos & Tests.
10M+ students study on EduRev
Related Searches

ppt

,

Summary

,

Sleep | Medical Science Optional Notes for UPSC

,

shortcuts and tricks

,

Objective type Questions

,

practice quizzes

,

Semester Notes

,

pdf

,

Sleep | Medical Science Optional Notes for UPSC

,

Viva Questions

,

mock tests for examination

,

Sample Paper

,

Sleep | Medical Science Optional Notes for UPSC

,

video lectures

,

Free

,

Exam

,

study material

,

MCQs

,

past year papers

,

Extra Questions

,

Previous Year Questions with Solutions

,

Important questions

;