1.
https://www.youtube.com/chann
el/UCAiarMZDNhe1A3Rnpr_WkzA
Saba Parvin Haque
MSc in Neuroscience
from “Sophia College For
Women”, Mumbai.

2.
Differences
between Rem &
non-rem
Source (Amlaner et al., 2003)

3.
Sleep is an essential life process.
It is as important to our well-being as the food we eat, the water we
drink, and the air we breathe.
Lack of sleep reduces our alertness, impairs our judgment, and affects
our moods.
Impairments to alertness and judgment due to sleep deprivation not only
lead to a loss of productivity at school or work, but also contribute to
increased accident rates.
Sleep is a behavioral state that is a natural part of every individual’s life.
We spend about one-third of our lives asleep.
Sleep is not a passive event, but rather an active process involving
characteristic physiological changes in the organs of the body.
In practice, EEGs, EOGs, and EMGs are recorded
simultaneously on continuously moving chart paper or digitized
by a computer and displayed on a high-resolution monitor. The
patterns of activity in these three systems provide the basis for
classifying the different types of sleep. Two basic stages, or
states, of sleep:
• Non–rapid Eye Movement (NREM) and
• Rapid Eye Movement (REM).
Source (Amlaner et al., 2003)
INTRODUCTION
https://images.app.goo.gl/cTssVkCGryN1wKjX8

4.
There are two basic types of sleep in a sleep cycle:
REM sleep consists of about 20%-25% of total sleep in adults.
Non-REM (NREM) sleep uses significantly less energy than REM sleep.
This type of sleep is associated with the brain restoring its supply of
adenosine triphosphate (ATP).
Rapid Eye
Movement
(REM)
Non-Rapid Eye
Movement
(NREM)
REM sleep is initiated through acetylcholine secretion and inhibited by
neurons that secrete monoamines including serotonin.
During REM, most muscles experience temporary paralysis.
This is also the stage during which people experience dreams.
NREM
Stage 1
(N1)
NREM
Stage 3 & 4
(N3 & N4)
NREM
Stage 2
(N2)
TYPES
Each of these stages can last from 5 to 15 minutes or more and NREM
stages may repeat until REM sleep is attained.
The percentage of REM sleep in adults changes little over the lifespan,
while slow-wave sleep tends to decline with age.
The longest REM period occurs at the end of a night’s sleep and is cut short
if a person does not get their full night of sleep.

5.
NREM
Stage 1
(N1)
• NREM stage 1 sleep serves a transitional role
in sleep-stage cycling.
• Aside from newborns and those with narcolepsy
and other specific neurological disorders, the
average individual’s sleep episode begins in
NREM stage 1.
• This stage usually lasts 1 to 7 minutes in the initial
cycle, constituting 2 to 5 percent of total sleep, and
is easily interrupted by a disruptive noise.
• Brain activity on the EEG in stage 1 transitions
from wakefulness (marked by rhythmic alpha
waves) to low-voltage, mixed-frequency waves.

6.
NREM
Stage 2
(N2)
• Stage 2 sleep lasts approximately 10 to 25 minutes in
the initial cycle and lengthens with each successive
cycle, eventually constituting between 45 to 55
percent of the total sleep episode.
• An individual in stage 2 sleep requires more intense
stimuli than in stage 1 to awaken.
• Brain activity on an EEG shows relatively low-
voltage, mixed-frequency activity characterized by the
presence of sleep spindles and K-complexes.
• It is hypothesized that sleep spindles are important for
memory consolidation.
• Individuals who learn a new task have a significantly
higher density of sleep spindles than those in a control
group.

7.
NREM
Stage 3 & 4
(N3 & N4)
• Sleep stages 3 and 4 are collectively referred to as slow-
wave sleep (SWS), most of which occurs during the first
third of the night.
• Each has distinguishing characteristics.
• Stage 3 lasts only a few minutes and constitutes about 3
to 8 percent of sleep.
• The EEG shows increased high-voltage, slow-wave
activity.
• The last NREM stage is stage 4, which lasts
approximately 20 to 40 minutes in the first cycle and
makes up about 10 to 15 percent of sleep.
• The arousal threshold is highest for all NREM stages in
stage 4.
• This stage is characterized by increased amounts of high-
voltage, slow-wave activity on the EEG

8.
https://images.app.goo.gl/ag3DcbJKSe9gR1ez9

9.
Fig: Sleep cycle and associated waveforms
Source: https://youtu.be/v5DUPLI580g
Fig: Sleep cycle and associated waveforms

10.
Comparison/differences of Physiological Changes
During NREM and REM Sleep
SOURCES: NHLBI (2003), Somers et al. (1993), Madsen et al. (1991b).

11.
Case Report of Rapid-eye-movement
(REM) sleep behavior disorder
• A 23-year-old female student presented with a five-year history of abnormal sleep in which
she would sit up or stand up for brief periods in the early morning, talk loudly for a couple of
minutes and then lie back down.
• When woken by family members she would remember vivid dreams and nightmares.
• In one episode she had a fall that resulted in a subdural hematoma.
• On presentation at the psychiatric hospital she had a normal mental status exam except for being
mildly depressed and anxious about the chronic fatigue from poor sleep.
• Overnight polysomnography (PSG) showed multiple waking periods each night, poor sleep
efficiency and a lack of normal muscle paralysis during REM sleep.
• The patient was diagnosed with REM Sleep Behavior Disorder and treated with 1 mg
clonazepam nightly.
• Her sleep improved dramatically and remained better at a six-month follow-up, but repeat PSG
exam found that the lack of muscle paralysis during REM sleep remained.

12.
Figure: Polysomnographic recording of the patient during REM sleep
prior to treatment
Source: Fan,Z. et al., (2013)

13.
Case Report of Non-Rapid-eye-movement (NREM)
sleep behavior disorder
• Female of 26 years old, was frequent lucid dreamer (one lucid dream a week) and a good dream re-
caller (a few dreams a week).
• Eye-signalling during NREM Stage 2 sleep occurred on a second consecutive night in the sleep
laboratory, during the second sleep cycle, 105 min after falling asleep.
• There was a descending N2 (starting 4 epochs before the signal), which was preceded by wakeful-ness and
N1 sleep.
• The sleep recording with two epochs preceding the signal is presented in the figure.
• When asked in the morning, the participant confirmed eye-signalling in the beginning of the night.
• She reported that there was no any visual imagery present, but there was a floating sensation without feeling
her body, therefore she realised that it has to be a dream and gave the eye-signal.
• Lucid dreams – dreams in which the dreamer is aware that is dreaming – most frequently occur during REM sleep, yet
there is some evidence suggesting that lucid dreaming can occur during NREM sleep as well.
• By conducting a sleep laboratory study on lucid dreams, they found possible instances of lucidity during NREM sleep
which are reported here in this case.
• While lucid dreaming during NREM sleep seems to be much rarer and more difficult to achieve, it appears to be possible
and is most likely to occur during N1 sleep, somewhat less likely during N2 sleep and yet to be observed during N3 sleep.

14.
Figure: Case; Eye-signal with two epochs preceding it.
Source: Stumbrys et al., (2012)

15.
REFERENCES
• Amlaner, Charles & Greene, Robert & Hanson, Michael & Nichols, Greg & Rogers, Naomi &
Thibodeau, Carol. (2003). Sleep, Sleep Disorders, and Biological Rhythms. Charles J. Amlaner.
• HF, A. (2018). The Science of Dreams and Biochemistry of Midnight: A Questionnaire Study.
International Journal of Biomedical Investigation, 1(2), q-18. https://doi.org/10.31531/2581-
4745.1000109
• Jacobson, K. (n.d.). Stages of Sleep: NREM Sleep vs REM Sleep. .
https://www.aastweb.org/blog/stages-of-sleep-nrem-deep-sleep-vs-rem-sleep
• Institute of Medicine (US) Committee on Sleep Medicine and Research; Colten HR, Altevogt BM,
editors. Sleep Disorders and Sleep Deprivation: An Unmet Public Health Problem. Washington
(DC): National Academies Press (US); 2006. 2, Sleep Physiology. Available from:
https://www.ncbi.nlm.nih.gov/books/NBK19956/
• Fan, Z., Niu, Y., & Zhang, H. (2013). Case Report of Rapid-eye-movement (REM) sleep
behavior disorder. Shanghai archives of psychiatry, 25(2), 121–123.
https://doi.org/10.3969/j.issn.1002-0829.2013.02.010
• Stumbrys, Tadas & Erlacher, Daniel. (2012). Lucid dreaming during NREM sleep: Two case
reports. International Journal of Dream Research. 5. 151-155. 10.11588/ijodr.2012.2.9483.

16.
Thank You