Sleep

Why is sleep important?

Essential for normal brain and body function

Complex, dynamic process

Biologic purpose not fully understood, but crucial for life

Sleep deprivation can be fatal (in animals)

Drug therapies aim to improve sleep quality and quantity

What is a chronotype and how does it affect sleep and productivity?

Is the natural preference for sleep/wake times

Morning person (early bird) → wakes early, most productive in the morning

Night person (night owl) → wakes later, productive at night

Influenced by: age, environment, activity and can be altered if desired

Early risers: tend to be happier and have lower depression risk

What is sleep?

Synchronized CNS neuronal activity

Reduced consciousness, but brain remains active

Voluntary activity is “paralyzed” by pons region of brain → Structure links medulla oblongata and thalamus

Biologically necessary

Humans spend ~1/3 of life sleeping

Why do we sleep?

Supports brain function, neuronal communication, and amyloid removal

Affects almost every tissue, organ, and system

Lack of proper sleep increases risk of → Hypertension, Heart disease, Diabetes, Depression, Obesity, Essential for normal function

Which CNS structures are involved in sleep and what are their roles?

Hypothalamus → Sleep, arousal, learning

Suprachiasmatic nucleus (SCN) → Responds to light, controls rhythms, signals pineal gland → melatonin

Brain stem (pons & medulla) → Sleep–wake transitions, reduces muscle/body movement

Thalamus → Quiet in non-REM; active in REM → dreams

Cerebral cortex → Cognition

Forebrain: Promotes sleep/wake; adenosine → sleep drive

Midbrain →Arousal

Amygdala → More active in REM sleep

What factors regulate normal sleep?

Morning light → resets circadian rhythm

Individual circadian rhythm & sleep–wake balance

Hormones:

• Melatonin ↑ in evening

• Cortisol ↓ in evening

Which neurotransmitters help produce sleep?

GABA → reduces brain activity

Orexin/hypocretin → secreted in evening

Others → serotonin, norepinephrine, adenosine, acetylcholine, histamine, epinephrine

What are the early stages of sleep?

Sleep latency → time from wakefulness to sleep

Hypnagogia → transitional state between wakefulness and sleep → drifting off

N1/Stage 1 → light sleep, slow heartbeat/breathing/eye movements, muscles relax, may have hypnic jerks

N2/Stage 2 → slower heartbeat & breathing, more muscle relaxation, body temp drops, eye movements stop

What are deep sleep and REM sleep stages?

N3/Stage 3/4: → deepest non-REM sleep, lowest heartbeat/breathing, very relaxed, hard to awaken

REM sleep → rapid eye movement, brain/body activity like awake, dreaming occurs

What factors can affect sleep quality and quantity?

Medical conditions: GERD, asthma, COPD, CHF

Stress & anxiety

Sleep environment: comfort, low noise/light

Eating near bedtime: large meals, high-calorie, spicy foods

Alcohol & caffeine before bed

Medications

Light exposure

Time changes: daylight savings, travel across time zones

What is dreaming?

CNS creates stories/images during sleep

Normal, may not be remembered

Purpose unknown: may help process information, events, emotions, memory

Can occur in any sleep stage, most vivid in REM sleep

Stress/anxiety → nightmares/night terrors

Dreams can be in color or black & white

Animals like dogs also dream

What are common sleep-related problems?

Breathing & airway → snoring, sleep apnea

Sleep difficulty → insomnia, restless-leg syndrome, sleep deprivation

Abnormal behaviors → sleepwalking, sleep eating, sleep driving, phone use

Excessive sleepiness → idiopathic hypersomnia, narcolepsy, microsleeps

Timing issues → circadian rhythm disorders (jet lag, shift work)

How much sleep is needed by age group?

Infants 0–3 mo: 14–17 h

Infants 4–11 mo: 12–15 h

Toddlers 1–2 yr: 11–14 h

Preschool 3–5 yr: 10–13 h

School-age 6–13 yr: 9–11 h

Teen 14–17 yr: 8–10 h

Adults: 7–9 h (some 6–10 h)

Older adults 65+: 7–8 h

Pregnancy (1st trimester): may need extra sleep

How is sleep evaluated?

Physical exam

EEG (brain waves):

• Alpha: 8–12 Hz (relaxed)

• Beta: 13–38 Hz (alert)

• Delta: 1–3 Hz (deep sleep)

• Theta: 4–7 Hz (dreamy)

• Gamma: 39–42 Hz (perception/consciousness)

Sleep study (polysomnography) → monitors heart rate, movement, brain activity, and breathing in a sleep lab

How does melatonin promote sleep?

Endogenous melatonin is made from tryptophan

Binds CNS receptors → inhibits cAMP signaling → reduces wakefulness

Exogenous melatonin or ramelteon mimics this effect

How do CNS depressants promote sleep?

Reduce activity of CNS neurons

Examples: barbiturates, some antidepressants, antihistamines

How do benzodiazepines help with sleep?

Bind GABA-A receptors in the brain

Reduce sleep latency (fall asleep faster)

Increase total sleep time

Typically used short-term for insomnia

Ex: Estazolam, Flurazepam, Temazepam, Quazepam, Triazolam

What are non-benzodiazepine GABA receptor agonists and their effects?

Enhance GABA activity → reduce neuronal excitability

Used for insomnia

Ex: Eszopidem (Lunestra), Zaleplon (Sonata), Zolpidem (Ambien)

May cause complex sleep behaviors → sleepwalking, sleep eating, sleep driving

What are Dual Orexin Receptor Antagonists (DORAs) and how do they work?

Bind both orexin receptors in lateral hypothalamus → block wake-promoting signals

Reduces activity of wake-promoting neurotransmitters

Orexin normally promotes wakefulness

Ex: Suvorexant (Belsomra), Daridorexant (Ouviviq), Lemborexant (Dayvigo)

What are the risks and side effects of sleep-inducing agents?

Daytime sedation

“Brain fog” (slowed thinking & cognition)

Impaired decision-making

Short- and long-term memory effects

Habit-forming potential (varies by agent)

Parasomnias (sleepwalking, sleep driving)

Dangerous with alcohol or other sedatives (additive/synergistic effects)

What are the risks of sleeping too much?

Diabetes

Obesity

Headaches

Back pain

Depression

Heart disease

Possibly increased risk of death

What are common causes of excessive daytime sleepiness?

Narcolepsy

Idiopathic hypersomnia

Cataplexy

What are the main treatments for excessive daytime sleepiness?

1. Oxybate salts (GHB) – CNS depressants

• Relax CNS, improve nighttime sleep → better daytime alertness

• May cause confusion, memory loss (worse with alcohol)

  • Xyrem → sodium oxybate

  • Xywav → calcium, magnesium, potassium, sodium oxybates

2. CNS stimulants – increase wakefulness

• Pitolisant (Wakix) → boosts histamine in brain (H3 receptor)

• Amphetamines → classic stimulants

How can jet-lag or shift-work sleep disorder be managed?

Modafinil / Armodafinil → promote wakefulness

Caffeine → blocks adenosine, boosts alertness

Adjust sleep schedule to usual routine when possible

How does switching between Standard Time and Daylight Savings Time affect sleep, and how can you adjust?

Alters circadian rhythm; harder to wake when it’s dark

Fall back → gain 1 hour; Spring forward → lose 1 hour (harder)

May worsen sleep for shift workers or those with seasonal affective disorder

Adjustment tip: shift bedtime 15–30 min for a few days before the change

What are some alternative approaches to improve sleep, even if evidence is limited?

Mind-body techniques: Meditation, yoga, mindfulness, biofeedback, hypnosis, acupuncture

Environmental aids: Weighted blankets, white noise, gentle wind/ocean sounds, soothing music

Lifestyle: Exercise 3–4 hrs before bed, warm bath

Supplements/herbals: Magnesium, chamomile tea, valerian root, lavender, kava-kava, ginkgo biloba

Aromatherapy

What factors should you check in an environmental sleep audit?

Room temperature → Too hot or too cold

Light exposure → Darkness or artificial light in room

Bed comfort → Mattress, pillow, sheets, blanket

Evening routine → Screen time, social media, scary movies, stress

Substances → Drugs, medications affecting sleep

Sleep quality vs. sedation → Natural sleep is different from being “knocked out”

What is sleep hygiene?

Practices, habits, and strategies that promote good quality sleep

Helps you wake up refreshed and alert

Prevents sleep problems

Sleep should be restful and restorative

How can you improve sleep quality?

Keep a consistent sleep schedule (bedtime & wake time)

Exercise ~30 min/day, several hours before bed

Avoid caffeine, nicotine late; limit alcohol before bed

Eat dinner 3–4 hours before bedtime

Disconnect from screens & reduce distractions

Take a relaxing bath or shower

Relax → read, meditate, use soothing sounds

Track sleep with an app or wearable