What are the most common sleep disorders?

The most common sleep disorders are insomnia, obstructive sleep apnoea, and restless legs syndrome. Circadian rhythm disorders such as shift work sleep disorder are also frequent, particularly in people working non-standard hours.

How much sleep do adults need?

Most adults need 7–9 hours per night. Consistently sleeping fewer than 6 hours is associated with increased risk of depression, cardiovascular disease, and metabolic dysfunction regardless of perceived tolerance.

When should I see a doctor about sleep problems?

See a doctor if sleep problems persist for more than 3 months, occur at least 3 nights per week, significantly impair daytime functioning, or are accompanied by loud snoring, witnessed breathing pauses, or excessive daytime sleepiness.

What is the best treatment for insomnia?

Cognitive behavioural therapy for insomnia (CBT-I) is the first-line treatment recommended by international guidelines. It addresses the thoughts and behaviours that perpetuate insomnia and produces more durable results than sleeping pills.

Sleep Health Hub

Introduction

Sleep is not passive downtime. It is a biologically essential process during which the brain consolidates memories, clears metabolic waste, regulates hormones, and restores immune function. A third of adults in high-income countries regularly sleep less than the recommended 7–9 hours — most without recognising the cumulative cost.

Poor sleep does not stay confined to the night. The evidence consistently links disrupted or insufficient sleep to heart disease, weight gain, type 2 diabetes, depression, anxiety, cognitive decline, and accelerated biological ageing.

This hub is the central navigation point for all PatientGuide sleep content.

Why Sleep Matters

Heart disease and blood pressure Short sleep duration and disturbed sleep raise blood pressure, increase inflammatory markers, and contribute independently to heart attack and stroke risk. Obstructive sleep apnoea is an independent risk factor for atrial fibrillation, heart failure, and stroke. See Heart & Circulation — Guide Hub and High Blood Pressure.

Obesity and metabolism Sleep restriction of even a few nights impairs insulin sensitivity and disrupts hunger hormones — raising ghrelin (appetite) and suppressing leptin (satiety). Poor sleep is an independent risk factor for insulin resistance and type 2 diabetes. See Obesity and Metabolic Health.

Mental health Sleep and mental health are bidirectional. Poor sleep worsens depression and anxiety; both conditions disrupt sleep. Treating insomnia independently improves mental health outcomes, including antidepressant response.

Memory and dementia risk The glymphatic system — the brain’s waste-clearance network — is most active during deep slow-wave sleep, clearing amyloid-beta and tau proteins implicated in Alzheimer’s disease. Chronic poor sleep is an independent risk factor for mild cognitive impairment and dementia. See Brain Health Hub.

Ageing and longevity Chronic sleep deprivation accelerates biological ageing at the cellular level and is associated with reduced longevity in population studies. See Ageing and Longevity Basics.

Common Sleep Problems

What Is Insomnia?

Insomnia is the most common sleep disorder — difficulty falling asleep, staying asleep, or waking too early on at least three nights per week. Understand the difference between acute and chronic insomnia, what the 3P model explains about why it persists, and how it is treated.

Sleep Apnoea — Causes, Risks, and Treatment

Obstructive sleep apnoea (OSA) occurs when the upper airway repeatedly collapses during sleep, causing breathing pauses and oxygen desaturation. It is seriously underdiagnosed, particularly in women, and carries major cardiovascular and metabolic risk if left untreated.

Restless Legs Syndrome

Restless legs syndrome (RLS) causes uncomfortable sensations in the legs — an irresistible urge to move — that worsen at rest and in the evening, directly disrupting sleep onset. Iron deficiency is a key modifiable cause.

Shift Work Sleep Disorder

People working nights, early mornings, or rotating shifts are at high risk of this circadian rhythm disorder. It causes difficulty sleeping at the required time and excessive sleepiness during work, with significant long-term health consequences.

Better Sleep

Healthy Sleep Hygiene

The evidence-based daily habits — consistent schedules, morning light exposure, caffeine timing, screen curfews, and bedroom environment — that form the behavioural foundation of healthy sleep.

Cognitive Behavioural Therapy for Insomnia (CBT-I)

CBT-I is the first-line treatment for chronic insomnia per international guidelines. It retrains the thoughts and behaviours that perpetuate sleeplessness and is more effective long term than any sleeping pill.

Melatonin: Benefits, Risks, and Safe Use

Melatonin is best used for shifting sleep timing — jet lag, shift work, and delayed sleep phase syndrome — not as a general sleep aid. Understand what the evidence supports, effective dosing, and what melatonin cannot do.

When to Seek Help for Insomnia

How to know when occasional poor sleep has crossed the threshold into something that warrants professional assessment, what to expect at that appointment, and how to access CBT-I.

Symptoms

Why Am I Always Tired?

Persistent tiredness has many potential causes beyond inadequate sleep — including sleep apnoea, depression, thyroid disease, iron deficiency anaemia, and diabetes. A practical differential guide, with clear signposting on when to seek medical investigation.

Why Sleep Matters — In Detail

Blood pressure The blood pressure dip that normally occurs during sleep (“nocturnal dipping”) is reduced or absent in people with poor sleep quality and untreated sleep apnoea. Over years, this raises cardiovascular risk independently of daytime blood pressure.

Weight and appetite Even two nights of partial sleep deprivation raises ghrelin by up to 28% and reduces leptin by 18% in controlled studies. Across a population, this contributes to progressive weight gain and worsens the obesity-diabetes cycle.

Mood and emotional regulation The amygdala becomes substantially more reactive after sleep deprivation, driving heightened anxiety, irritability, and emotional lability. This is one reason poor sleep and mental health conditions are so strongly linked.

Cognition Memory consolidation — the transfer of experiences from short-term to long-term storage — occurs during slow-wave and REM sleep. Even modest sleep restriction impairs working memory, attention, and decision-making measurably the following day.

Dementia risk The glymphatic system clears amyloid and tau from the brain predominantly during deep slow-wave sleep. Chronic sleep restriction reduces glymphatic clearance and is associated with higher amyloid deposition on imaging studies — suggesting sleep is not just a correlate but a mechanism in dementia pathogenesis. See Dementia: Early Signs, Causes, and Prevention.

Educational only; not a substitute for professional medical advice.