Source: Lecture Notes 3–4, Textbook pp. 222–228
Difficulty: Introductory. Prerequisites: None beyond basic familiarity with health psychology terminology from earlier weeks.
This set of notes covers two remaining health promotion topics from Week 4: sleep (its stages, its health consequences, and strategies for improving it) and obesity (its scope as a public health crisis and the factors that drive it). Both connect to the exercise and diet material covered in the companion study notes. Sleep is a modifiable health behaviour that affects cognitive functioning, mood, and physical health. Obesity is framed as a complex, multi-level problem influenced by biology, psychology, environment, and society.
Sleep cycles through NREM stages (light to deep) and REM, each serving different restorative and cognitive functions. Insufficient sleep impairs memory, mood, job performance, and physical health, while too much sleep is linked to psychopathology. Obesity affects over 70% of Americans and is driven by interacting factors across biology, psychology, food environment, and societal influences, not individual willpower alone.
Non-Rapid Eye Movement (NREM) sleep
The first three stages of sleep, progressing from light sleep (Stage 1) through deep sleep (Stages 3 and 4). NREM sleep is primarily restorative.
Think of it as the phase where your body does its repair work: restoring energy, strengthening the immune system, and releasing growth hormone.
Rapid Eye Movement (REM) sleep
The sleep stage that follows NREM, characterised by rapid eye movements, variable breathing and heart rate, dreaming, and beta wave activity. REM sleep is primarily cognitive.
Think of it as the phase where your brain does its filing: consolidating memories, processing problems, and converting knowledge into long-term storage.
Theta waves
Brain waves associated with Stage 1 (light) NREM sleep.
In simple terms, these are the brain's signal that you are just drifting off.
Sleep spindles and K-complex waves
Brain wave patterns characteristic of Stage 2 NREM sleep, during which breathing and heart rate even out and body temperature drops.
Delta waves
Slow brain waves associated with Stages 3 and 4 (deep) NREM sleep.
In simple terms, delta waves mean you are in the deepest, most restorative phase of sleep.
Beta waves
Brain waves typically associated with waking alertness, but also present during REM sleep.
Obesity
A condition defined by a BMI of 30 or above, widely recognised as a public health epidemic with multiple interacting causes across biology, psychology, food environment, and societal influences.
In simple terms, it is not simply about eating too much; it is a complex condition shaped by everything from genetics to the food industry to neighbourhood design.
Foresight Report
A UK government report that provides a framework for understanding obesity as a multi-level, multi-cause problem, mapping the interactions between societal influences, individual psychology, food environment, food consumption, physical activity, activity environment, and biology.
Stage 1
Lightest and earliest stage of sleep
Marked by theta waves
Easy to be woken from this stage
Stage 2
Breathing and heart rates even out
Body temperature drops
Brain waves alternate between sleep spindles and K-complex waves
Stages 3 and 4
Deep sleep stage
Marked by delta waves
A good portion of total sleep is spent in NREM sleep
Restores energy
Strengthens the immune system
Prompts the body to release growth hormone that repairs damage sustained during the day (e.g., tiny muscle tears are generally repaired during this stage)
After the three NREM stages, you move into REM sleep.
Characteristics:
Eyes move back and forth
Breathing and heart rates become variable
Dreams occur
Marked by beta waves (the same waves seen during waking alertness)
Functions of REM sleep:
Consolidating memories
Solving problems encountered during conscious waking hours
Converting knowledge into long-term memories
Insufficient sleep affects:
Cognitive functioning (memory, ability to pay attention)
Mood (poor sleep leads to negative mood)
Job performance
Quality of life
Physical health
Reasons for lack of sleep:
Stress, high levels of hostility, or arousal
Usage of maladaptive coping strategies
Worrying about the causes of stress
Consuming alcohol
Note: sleeping for excessively long hours can also result in psychopathology. Both too little and too much sleep are problematic.
Relaxation and renewal help people:
Savour the positive aspects of life
Reduce stress
Restore emotional balance
Participation in enjoyable activities lowers blood pressure, cortisol, and weight, and improves physical and cognitive functioning.
Get regular exercise, at least three times a week
Keep the bedroom cool at night
Sleep in a comfortable bed that is big enough
Establish a regular schedule for waking and going to bed
Develop nightly rituals (e.g., taking a shower)
Use a fan or noise generator to mask background sound
Avoid excessive alcohol and smoking
Avoid eating too much or too little at night
Avoid strong smells in the room (incense, candles, lotions)
Avoid napping after 3 p.m.
Cut back on caffeine in the afternoon or evening
If awakened, get up and read quietly in another place, so that bed is associated with sleep rather than sleeplessness
Obesity is widely recognised as a complex, multi-level issue. The Foresight Report (UK) provides a useful framework, mapping the interactions between:
Societal influences
Individual psychology
Food environment
Food consumption
Physical activity
Activity environment
Biology
All of these layers interact, which is why single-factor explanations ("people just eat too much") are inadequate.
71.6% of Americans are overweight or obese (2015–16 data)
Lifespan events that can cause weight gain include:
Quitting smoking: associated with weight gain over the subsequent 5 years for 80% of people, with women tending to gain more than men
For women specifically: breastfeeding, menarche, pregnancy, and menopause are all associated with weight changes
Students often mix up which brain waves belong to which sleep stage. Remember: theta (Stage 1), sleep spindles and K-complexes (Stage 2), delta (Stages 3–4), beta (REM).
Students sometimes assume REM is the "deepest" sleep because dreaming feels intense. Stages 3 and 4 NREM are the deepest stages. REM brain activity resembles waking.
Students may think that more sleep is always better. The lecture notes that sleeping for excessively long hours can result in psychopathology.
Students sometimes treat obesity as purely an individual choice. The Foresight Report framework emphasises that obesity is shaped by interacting biological, psychological, environmental, and societal factors.
⚠️ Know the brain wave type for each sleep stage (theta, spindles/K-complexes, delta, beta). This is a classic exam question.
⚠️ Be able to distinguish the functions of NREM sleep (restorative: energy, immune system, growth hormone) from REM sleep (cognitive: memory consolidation, problem-solving, long-term memory conversion).
⚠️ Know at least four reasons for insufficient sleep and four consequences of insufficient sleep.
⚠️ The Foresight Report's seven interacting factors are likely testable as a framework for understanding obesity.
⚠️ Know the 71.6% statistic for American overweight/obesity rates and the lifespan factors that contribute to weight gain (quitting smoking, female reproductive milestones).
Stage 1 NREM sleep is marked by __________ waves. Theta.
True or False: REM sleep is the deepest stage of sleep. False. Stages 3 and 4 NREM are the deepest. REM brain activity resembles waking.
During REM sleep, the brain consolidates __________ and converts knowledge into __________. Memories; long-term memories.
True or False: Approximately 50% of Americans are overweight or obese. False. The figure is 71.6% (2015–16).
The __________ Report (UK) provides a multi-level framework for understanding obesity. Foresight.
Q: List the four stages of NREM sleep and the brain wave type associated with each.
A: Stage 1 is marked by theta waves. Stage 2 features sleep spindles and K-complex waves. Stages 3 and 4 are marked by delta waves and represent the deepest sleep.
Q: What are the three main functions of REM sleep?
A: Consolidating memories, solving problems encountered during waking hours, and converting knowledge into long-term memories.
Q: Name four consequences of insufficient sleep.
A: Impaired cognitive functioning (memory, attention), negative mood, reduced job performance, lower quality of life, and poorer physical health (any four).
Q: According to the Foresight Report, what are the interacting factors that drive obesity?
A: Societal influences, individual psychology, food environment, food consumption, physical activity, activity environment, and biology.
Q: Name two lifespan events associated with weight gain.
A: Quitting smoking (associated with weight gain for 80% of people over the following 5 years) and, for women, reproductive milestones such as pregnancy, menarche, and menopause.
This connects to exercise because regular exercise is one of the key recommendations for good sleep (Table 4.3) and is a central factor in obesity prevention. It connects to diet because dietary habits, stress-related eating, and obesity are all interlinked, and the interventions for modifying diet (motivational interviewing, self-monitoring, social engineering) apply to weight management as well. Stress appears as a common thread: it disrupts sleep, drives unhealthy eating, and contributes to the psychological factors in the Foresight obesity framework.
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