what are your three states of consciousness?

sleep, waking and dreaming


includes non-rem sleep (non-rapid eye movement); brain waves are high-voltage and slow wave


sensations are vivid and externally generated; rapid eye movement; brain waves are low-voltage, fast wave


REM sleep; sensations are vivid and internally generated; movements are absent; muscle paralysis is present; rapid eye movement; brain waves are low-voltage, fast wave

what are circadian rhythms?

24h to a 25h cycle; light-dark cycle;

what is the suprachiasmatic nucleus (SCN)?

master clock of the circadian rhythms; drives the sleep cycle; regulated by light in the environment; receives direct projections from the retina which entrain it to the actual day length of 24h; SCN projects indirectly to the pineal gland via spinal cord

how does the SCN project to the pineal gland?

indirectly via the spinal cord; connections from the SCN project to sympathetic preganglionic neurons in the spinal cord that project to the superior cervical ganglion; postganglionic neurons project form this ganglion to the pineal gland; cyclic of SCN s

what does the pineal gland secrete?


what is seasonal affective disorder?

SAD; is characterized by depressive symptoms in the winter months (the time with least amount of daylight!). This patient typically: eats a lot, sleeps a lot, and is tired, irritable, has a hard time concentrating, is unmotivated, and feels sad. Seasonal

what else fluctuates with circadian rhythms?

Growth hormone, cortisol levels in the blood, alertness and core body temperature fluctuate in specific patterns related to circadian rhythms.

serotonin correlation of sleep

helps initiate sleep, rises with onset of sleep and falls with waking

acetylcholine correlated with sleep

higher during REM sleep;

norepinephine correlated with sleep

lower during REM sleep; ratio of AHe and NE is biochemical trigger for REM sleep

dopamine correlated with sleep

produces arousal and wakefulness; rises with waking; falls with sleep onset

REM sleep occurs

every 90 minutes;

how many stages of non-REM sleep are there?

Non-REM sleep is characterized by slower EEG rhythms, higher muscle tone, an absence of eye movements, and an absence of "thought-like" mental activity. NREM sleep is an idling brain in a moveable body.

REM sleep

REM sleep is characterized by an aroused EEG pattern, sexual arousal, saccadic eye movements, elaborate visual imagery (associated with pons activity). REM sleep is an awake brain in a paralyzed body.
is characterized by beta waves, rapid eye movements, r

N1 sleep

is characterized by a transition of the brain from alpha waves (awake eyes closed) having a frequency of 8-13 Hz (awake state) to theta waves having a frequency of 4 -7 Hz. Also known as somnolence or drowsy sleep. Some subjects experience: sudden hypnic

N2 sleep

is characterized by sleep spindles (ranging 11-16 Hz) and K-complexes.
[Bruxism - "teeth grinding" may occur in this stage of sleep] Subjects experience decreased muscular activity. Conscious awareness of the external environment disappears. This stage oc

N3 sleep

is characterized by the presence of a delta waves (at least 20%) ranging from 0.5-2 Hz.
Subject may experience parasomnias e.g. night terrors, bed wetting (nocturnal enuresis ), sleep walking (somnambulism), sleep-talking (somniloquy). Note: sleep-talking

sleep architecture

normal sleep

For an individual who is living on a conventional sleep-wake schedule and who is without sleep complaints: (i) Sleep is entered through NREM. (ii) NREM sleep and REM sleep alternate with an initial cycle of approximately 90 minutes. Subsequent sleep cycle

REM with age

Both REM and total sleep time decline with age. With age, there is decreased REM and slow-wave sleep, increased sleep onset latency and increased early awakenings. Neonates spend most time in REM, elderly spend the least. For adults, about 20% of sleep ti

benefits of REM sleep

Sleep removes metabolites from the brain.
REM sleep increases somewhat after learning, especially learning complex material.
REM sleep is when conceptual, long-term memories are consolidated by the hippocampus.
REM "clears out the brain", providing unclut

what is sleep debt?

Most lost sleep is not recovered. For most people: getting only five hours of sleep at night means that they are functioning at the level of someone legally drunk. The cerebral cortex shows the greatest effects of sleep deprivation (the rest of body seems


Electroencephalogram (EEG): Classical method of recording brain rhythms from the cerebral cortex.
EEG is a measurement of generalized cortical activity. EEG is non-invasive, painless. EEG can be used to diagnose neurological conditions such as epilepsy, s


Records miniscule magnetic signals generated by neural activity. Like EEG, MEG measures neuron activity, and is non-invasive, and painless. MEG localizes sources of neural activity better than EEG. MEG is more expensive, and requires larger equipment than


is characterized by "sleep attacks" (at least three episodes per week over three months). Sleep attacks are intrusions of elements of REM sleep into periods of wakefulness. Patients have irresistible urges to sleep for brief periods during the day and alm


is a chronic inability to fall asleep. It is important to distinguish between the two types of insomnia: PRIMARY insomnia involves an abnormality in the sleep mechanism. In this condition there are no signs of a psychological or medical problem that could

sleep walking

is a type of Non-REM sleep arousal disorder which occurs in N3 delta sleep, in the first third of the night. It is more common in children than adults. This disorder is characterized by unusual autonomic and/or motor responses. Somnambulism typically take

night terrors

are a type of Non-REM sleep arousal disorder which occurs in N3 delta sleep, in the first third of the night. It is most common in children (and more common in males). Night terrors is a parasomnia that occurs soon after falling asleep. Entire episode las

sleep apnea

is characterized by repeated/periodic, short interruption of breathing.
The number of episodes per hour indicated the severity: mild= 5-15 episodes, moderate= 16-30 episodes, severe= >30 episodes. This disorder occurs more frequently in men (than women),

sleep-related hypoventilation

is characterized by a reduction in ventilatory response to hypoxia and increased arterial CO2 levels. Therefore, decreased respiration with elevated CO2 levels.
Patients may have a history of a preexisting disorder of hypoventilation, including diaphragm

restless leg syndrome

is characterized by a creeping or crawling (or tingling, burning, itching) feelings in the calves and thighs that occurs when the person begins to rest (or periods of inactivity). This discomfort may be temporarily relieved by movement of the legs. This s