Sleep Stages: NREM1, NREM2, NREM3

Sleep Purpose

• Sleep is essential, though its exact functions remain a mystery
• It serves roles in rejuvenation and repair
• Lack of REM sleep may induce psychosis, impacting mental health
• Amyloid levels in the brain and cerebrospinal fluid (CSF) are temporarily decreased during sleep
• Memory consolidation is a key function of sleep

Sleep Stages

• A full sleep cycle takes approximately 90 minutes and consists of 4-6 cycles
• Growth hormone is secreted mostly during stage 3

NREM Stage N1: Falling Asleep

• Heartbeat and breathing slow
• Muscles begin to relax
• This stage only lasts a few minutes
• Theta waves are present

NREM Stage N2: Light Sleep

• Heartbeat and breathing slow down further from stage N1
• There are no eye movements
• Body temperature drops
• Brain produces "sleep spindles"
• It lasts approximately 25 minutes

NREM Stage N3: Slow Wave Sleep

• It is the deepest sleep state
• Heartbeat and breathing are at their slowest rate
• There are no eye movements
• The body is fully relaxed
• Delta brain waves are present
• Tissue repair, growth, and cell regeneration occur
• The immune system strengthens
• Sleep inertia can occur if awoken during this stage
• Memory consolidation occurs

REM Stage R

• It is the primary dreaming stage
• Eye movements become rapid
• Breathing and heart rate increases
• Limb muscles become temporarily paralyzed
• Brain activity is markedly increased
• The brain and body are energized
• Amyloid is eliminated
• The stage can last 10-60 minutes
• Memory consolidation occurs

Maintenance of Sleep Cycle

• The circadian rhythm is a biologic cycle influencing sleep, cortisol and hormone realease, and temperature
• Routine, such as a consistent wake/sleep time, is important
• External cues, such as activity and eating, influence the sleep cycle
• Age is a factor in sleep cycle maintenance
• Daylight, meaning the time of light exposure and darkness, effects sleep

Role of Early AM Natural Light

• It synchronizes the circadian rhythm
• It facilitates wakefulness
• It affects melatonin production
• Light decreases melatonin
• Darkness increases melatonin, causing sleepiness

Sufficient Sleep

• Individual sleep needs vary greatly
• On average, 7-9 hours is optimal
• Some individuals can manage on as little as 4 hours
• Younger individuals generally require more sleep

Differences in Sleep with Increased Age

• Sleep becomes shallower, more fragmented, and shorter when aging
• Daytime sleepiness increases with age
• Shallower stages 1 and 2 increase, while deeper stages 3 and 4 decrease
• Over 30 minutes are required to fall asleep after age 65 (1 in 3 women, 1 in 5 men)
• Wakefulness after sleep onset (WASO) and the number of arousals increase due to sleep-related breathing disorders, periodic leg movements (PLMs), and other physical conditions.

Sleep Deprivation

• It is insufficient sleep to support adequate alertness, performance, and health
• Defined as less than 7 hours per night per DSM 5 TR

Sleep Deprivation Consequences: Impairment

• Medical residency hours often lead to errors and accidents
• Being awake for 18 hours (equivalent to 6 hours of sleep) equates to a BAC of 0.05%
• Being awake for 24 hours results in a BAC of 0.10%, the legal intoxication definition of 0.08%
• It is linked to airline crashes and nuclear disasters such as Three Mile Island and Chernobyl
• Chronic restriction of sleep to 4-6 hours/night over 14 days causes measurable impairment of waking neurobehavioral functions (somatic, cognitive, behavior, communication, and social)

Sleep Related MVA

• According to the AAA Foundation for Traffic Safety, getting just 5 to 6 hours of sleep in a 24-hour period doubles the risk of a motor vehicle accident (MVA)
• 100,000 police-reported crashes are the direct result of driver fatigue each year
• There are 633 deaths, 91,000 injuries, and $100 billion in monetary losses annually
• These figures are likely under reported

Key Steps to Prevent Falling Asleep Behind the Wheel

• Get the recommended 7-9 hours of sleep before a trip
• Plan long trips with a companion
• Schedule regular stops every 100 miles or 2 hours

Side Effects from Missing Sleep

• Sleeping less will increase the risk of depression and bipolar disorder
• Sleep deprivation can supress growth hormone

Insomnia Disorder: Diagnostic Criteria (DSM 5 TR)

• Diagnosed when there is a decrease in sleep quantity or quality, as well as one or more of the following
  • Difficulty initiating sleep
  • Difficulty maintaining sleep
  • Early-morning awakening
• Includes clinically significant distress that occurs at least 3 nights/ week for at least 3 months
• Must occur despite adequate opportunity for sleep

Prevention of Falling Asleep Behind the Wheel

• Get 7-9 hours of recommended sleep
• Plan long trips with a companion
• Schedule regular stops every 100 miles or 2 hours

Jet Lag

• Environmental desynchronization is caused by crossing multiple time zones
• This results in increased fatigue and clouded mentation
• The phase advance travel is usually harder to adjust to compared to phase delay
• The human circadian rhythm averages longer than 24 hours internally, but environmental cues such as sunlight and alarm clocks cause someone to adapt to a 24 hour rhythm

Treatment of Jet Lag

• Adapt slowly to a new time zone approximately 15min-1hr every night before a trip
• A person should maintain regular mealtimes
• Exercise is encouraged
• The jet lagged traveler should seek light exposure in a new time zone
• Melatonin and Caffeine supplements may help treat jet lag

Adjusting to Time Changes

• Adjustments should be the same as treating jet lag
• Caution should be used when performing dangerous activities 5-7 days after a change

Circadian Rhythm Sleep Disorder

• A person's own sleep-wake schedule is not synchronized with social schedule
• Insomnia and sleepiness occur regularly, but at a socially inopportune time

Circadian Rhythm Disorder Treatment

• Bright light therapy can be used; > 6000-10,000 lux for 30-60mins in a well-lit room
• Adjust behavior to improve overall health and create better opportunity for adequate sleep
• Melatonin supplement

Parasomnias

• Abnormal behavior and experiential/physiological events occur during specific sleep and sleep transition

REM Sleep Behavior Disorder Treatment

• Clonazepam can be prescribed indefinitely long-term
• There is low risk of resistance or augmentation
• Can be treated with Levodopa/Carbidopa but patients can develop resistance
• It is important to make a bedroom safe by removing firearms or weapons
• Referal to neurology should be made to evaluate neurodegenerative disorders

Restless Leg Syndrome

• There is an urge to move the legs from uncomfortable and unpleasant sensations:
  • It gets worse when the person rests (periods of inactivity) as dopamine levels fall
  • Movement provides a sense of relief from the discomfort
  • Symptoms can occur 3 times every week/3mon
• Psychiatric factors, stress, and fatigue can exacerbate RLS pathophysiology
• A central subcortical dopamine deficiency may also contirbute to RLS pathophysiology