Sleep deprivation: causes and effects (WACE Year 12 Psychology Unit 4)
“Sleep deprivation: causes (shift work, drugs, sleep environment, stressors); psychological and physiological effects of partial sleep deprivation (mood, attention, reflex speed, vision) and chronic sleep deprivation (heart disease, obesity, insomnia, anxiety)”
Sleep deprivation is getting less sleep than you need. The syllabus names four causes: shift work, drugs (such as caffeine, alcohol and nicotine), the sleep environment (light, noise, temperature, screens) and stressors. Partial sleep deprivation (some sleep, but not enough, over a short period) affects mood, attention, reflex speed and vision. Chronic sleep deprivation (not enough sleep over a long period) is linked to heart disease, obesity, insomnia and anxiety.
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What this dot point is asking
Expect to identify causes in a scenario, describe the short-term and long-term effects, and link them to health and safety.
Causes of sleep deprivation
| Cause | How it disrupts sleep | Example |
|---|---|---|
| Shift work | Working at night forces sleep during the day, against the body clock, and rotating rosters keep changing sleep times | Nurses, fly-in fly-out mine workers, police |
| Drugs | Stimulants delay sleep; alcohol may help people fall asleep but disrupts sleep later in the night, including REM sleep | Coffee or energy drinks in the afternoon, alcohol before bed, nicotine |
| Sleep environment | Light, noise, uncomfortable temperature or bedding, and devices in the bedroom make it harder to fall and stay asleep | A bright phone screen, traffic noise, a hot bedroom |
| Stressors | Worry and physiological arousal make it hard to fall asleep and cause waking during the night | Exams, relationship problems, financial worries |
Partial sleep deprivation: effects
Partial sleep deprivation means getting some sleep, but less than needed, over a short period (one or a few nights). Teenagers typically need about 8 to 10 hours a night.
- Mood: irritability, low mood, frustration and emotional overreaction.
- Attention: difficulty concentrating, lapses of attention (microsleeps) and poorer performance on tasks needing sustained focus.
- Reflex speed: slower reaction times, increasing the risk of accidents.
- Vision: blurred vision and difficulty focusing the eyes.
These effects are usually reversible with recovery sleep.
Chronic sleep deprivation: effects
Chronic sleep deprivation means regularly getting too little sleep over weeks, months or years, building a large sleep debt.
- Heart disease: long-term short sleep is linked to high blood pressure and a higher risk of heart disease.
- Obesity: sleep loss disrupts hormones that control hunger and fullness, increasing appetite and weight gain.
- Insomnia: ongoing poor sleep can become a persistent difficulty falling or staying asleep, as worry about sleep adds to arousal.
- Anxiety: chronic sleep loss is associated with higher anxiety and poorer emotional regulation, and anxiety in turn disrupts sleep.
Partial: short term, mainly psychological and performance effects (mood, attention, reflex speed, vision). Chronic: long term, health effects (heart disease, obesity, insomnia, anxiety).
Josh's exam block
Josh drinks two energy drinks each afternoon, studies on his laptop in bed until 1 am, and worries about his ATAR. He has slept five hours a night for the past three nights.
- Causes: drugs (caffeine in energy drinks), sleep environment (laptop screen in bed) and a stressor (worry about his ATAR).
- Type: partial sleep deprivation (a few nights of reduced sleep).
- Likely effects: irritability (mood), losing focus while studying (attention) and slower reactions if he drives to school (reflex speed).
- Risk: if the pattern continues for months it becomes chronic, raising his risk of insomnia and anxiety.
Marker's note: match each cause to the syllabus categories, then connect each effect to the scenario.
- Mixing up partial and chronic effects
- Heart disease and obesity are long-term effects of chronic deprivation; mood, attention, reflex speed and vision are the listed partial effects.
- Saying alcohol improves sleep
- It may make people fall asleep faster, but it disrupts sleep later in the night.
- Listing causes without explaining how they disrupt sleep
- Link each cause to a mechanism, such as arousal, light or the body clock.
Exam-style questions
Questions in the style of SCSA exam questions on this dot point, each with a worked answer. They are written by ExamExplained unless tagged "Past paper"; the year shows the paper a question is modelled on.
Original6 marksA truck driver has worked a series of night shifts and has slept only four hours in the past day. Describe three psychological or physiological effects of partial sleep deprivation that could make driving dangerous.Show worked answer →
Two marks for each effect described and linked to driving.
- Attention
- Sleep deprivation causes lapses of attention and difficulty concentrating, so the driver may miss a hazard or a change in traffic.
- Reflex speed
- Reaction time slows, so the driver takes longer to brake when a car stops suddenly.
- Vision
- Vision can become blurred and the eyes may struggle to focus, making it harder to judge distances and read signs.
- Mood
- Irritability can make the driver more likely to take risks or react aggressively to other drivers.
Original4 marksExplain the difference between partial and chronic sleep deprivation and give one health consequence of chronic sleep deprivation.Show worked answer →
Three marks for the distinction and one mark for a consequence.
- Partial sleep deprivation
- Getting some sleep, but less than the amount needed, over a short period such as one or a few nights. Its effects, such as low mood and poor attention, are usually reversed by catching up on sleep.
- Chronic sleep deprivation
- Regularly getting less sleep than needed over a long period (weeks, months or years), so the sleep debt builds up and effects become long-term.
- Consequence
- Any one of: increased risk of heart disease, obesity, insomnia or anxiety.
Practise this
Sources & how we know this
- Psychology ATAR course Year 12 syllabus (effective from 1 January 2024) — School Curriculum and Standards Authority (SCSA)
- Psychology ATAR course: syllabus and support materials — SCSA
- Past ATAR course examinations — SCSA