Individual Behaviour: Sleep and Dreams and Sleep Disorders Flashcards
Biological Approach: Circadian Rhythms
Circadian rhythms are physical processes mainteined by sunlight an dother times cues that keep the sleep-wake patterns on a consistent 24-hour schedule. Circadian functions inlcude; body temperature, hormone levels, and the sleep-wake cycle. In healthy people, hte circadian rhythms rise adn fall throughout the day adn night to signal wakefulness or sleepiness. While many people refer to circadian rhythms as a single process, there are actually a number of body clocks that oscillate throughout the day. For example, mental alertness tends to peak twice in a day at 9AM adn 9PM, while physical strength tends to crest at 11AM adn 7PM.
Biological Approach: Circadian Rhythms (Key Points)
- Circadian rhythms are tied to sunlight cues.
- Disrupting these patterns can lead to poor or difficult sleep.
- Without light signals, people tend to operate on a 25-hour schedule.
- Circadian rhythms also impact body temeprature, pain sensitivity, mental alertness, physical strength, and the senses.
Biological Approach: The Role of the Brain in Sleep
A tiny cluster of approx. 20,000 neurons in the hypothalamus controls your body’s many circadian rhytms. Known as the suprachiasmatic nucleus (SCN), this master control centre is responsible for acting as your body’s internal pacemaker. While the exact mechanisms for how this process works are unclear, environmental cues are important. Sunlight is perhaps the most apparent, controlling our daily sleep-wake schedule.
So how does sunnlight affect circadian rhythms? As the sunlight decreases at the close of the day, the visual system sends signals to the SCN. Next the SCN sends signals to the pineal gland to increase teh production of the hormone melatonin. This hormone increase helps reduced activity and makes you feel increasingly sleepy.
Babies: 14 to 15 hrs sleep
Toddlers: 12 to 14 hrs sleep
Pre-School: 11 to 13 hrs sleep
School Age Children: 10 to 11 hrs sleep
Adolescents: 8.5 to 9.25 hrs sleep
Adults, including Elderly: 7 to 9 hrs sleep
Preganant Women: 8 + hrs sleep
Biological Approach: Homeostasis
Homeostasis is any internal biochemical system that regulates the body’s internal environment, with a view to maintaining properties such as; temperature, acidity etc in a stable and relatively condition.
Sleep-wake homeostasis, in particular, can be thought of as a kind of internal timer or counter that generates a homeostatic sleep drive or pressure for sleep as a function of the amount of time elapsed since the last adequate sleep episode. It is quite intuitive in its operation: the longer we have been awake, the stronger the desire and need to sleep becomes and the greater the likelihood of falling asleep; the longer we have been asleep, the more the pressure to sleep dissipates, and the greater then likelihood of awkening.
Compared to teh circadian drive for arousal, the actual mechanism of sleep-wake homeostasis is relatively poorly understood, despite years of research. What is known is that a naturally produced sleep-regulating substance or substances, builds up in the body’s cerebrospindal fluid during our waking hours, which has the effect of increasing the pressure to sleep the more it accumulates. This pressure is only released by the act of sleeping itself, during which the levels of the sleep-regulating substance in the body rapidly declines.
The best known of these sleep-regulating substances (although probably not the only one) is adenosine. Adenosine operates as a neuromodulator in the brain, and has the effect of the inhibiting many of the bodily processes associated with wakefulness, particularly those involving the neurotransmitters adn serotonin.
Biological Approach: The 4 Stages of Sleep
Sleep begins in stage 1 and progresses into stages 2, 3 adn 4. After stage 4 sleep, stage 3 and then stage 2 sleep are repeated before entering rapid eye movement (REM) sleep. Once REM sleep is over, the body usually returns to stage 2 sleep. Sleep cycles through these stages approximately four or five times throughout the night. On average, we enter the REM stage approximately 90 minutes after falling asleep. The first cycle of REM sleep might last only a short amount of time, but ach cycle becomes longer. REM sleep can last up to an hour.
Biological Approach: Drowsy Resting (Just as we Fall Asleep)
More synchronised alpha waves, heart rate slows, temperature falls and mucle tension reduces.
Biological Approach: Stage 1 of Sleep
Stage 1 is the beginning of the sleep cycle, and is a relatively light stage of sleep. Stage 1 can be considered a transition period between waefulness and sleep. In Stage 1, the brain produces high amplitude theta waves, which are very slow brain waves. This period of sleep lasts only a brief timme (around 5-10 mins). If you awaken someone during this stage, they might report that they weren’t really asleep. There is less desynchronised brain activity during this stage and you may experience Hypnic Myoclonia.
Biological Approach: Stage 2 of Sleep
Stage 2 is the second stage of sleep and lasts for approximately 20 mins. The brain begins to produce bursts of rapid, rhythmic brain wave activity known as sleep spindles. Body temperature starts to decrease and heart rate begins to slow. There is synchronised brain activity and muscle tensions is reduced.
Biological Approach: Stage 3 of Sleep
Deep, slow brain waves known as delta waves begin to emerge during stage 3 sleep. Stage 3 is a transitional period between light sleep and a very deep sleep. There is less sleep spindles and heart, breathing rate continue to fall.
Biological Approach: Stage 4 of Sleep
Stage 4 is sometimes referred to as delta sleep because of the slow brain waves known as delta waves that occur during this time. Stage 4 is a deep sleep that lasts for approx. 30 mins. Bed-wetting and sleepwalking are most likely to occur at teh end of stage 4 sleep. Only delta waves happen during this stage. there is synchronised brain activity, night terrors and sleepwalkiing can occur at this stage.
Biological Approach: Stage 5 of Sleep (REM Sleep)
Most dreaming occurs about an hour after we fall asleep during the 5th stage of sleep, known as rapid eye movement (REM) sleep. Dreaming occurs durinng REM sleep and is characterised by the rapid and random movement of the eyes as well as increased respiration rate and increased brain activity There are around 3 to 5 REM episodes a night. Breathing becomes irregular, there is temporary sleep paralysis adn blood pressure rises. EEGs show REM brain waves are similar to those of wakefulness, there is desynchronised brain activity adn this stage lasts approximately 90 mins.
Biological Approach: REM Sleep and Dreaming
REM sleep is also referred to as paradoxical sleep because while the brain and other body systems becomoe more active, muscles become more relaxed. Dreaming occurs because of increased brian activity, but voluntary muscles become paralysed. REM sleep inn adult humans typically occupies 20-25% of total sleep, about 90-120 mins of a night’s sleep.
Biological Approach: Non-REM Sleep
Non-REM sleep occurs at the beginning of the sleep cycle and the first stage of sleep cycle is a relatively light stage of sleep lasting approx. 5-10 mins.
Stage 2 of the sleep cycle and lasts for approx. 20 mins. The brain begins to produce bursts of activity known as sleep spindles.
Stage 3 of Non-REM sleep is a transition between light adnd deep sleep. Stage 4 is a deep sleep when sleepwalking or bedwetting is most likley to occur.
The brain produces very slow brain waves known as theta waves adn heart-rate slows and body temperature drops.
Biological Approach: Factors Affecting Sleep - Environmental (Light)
Artificial lighting makes it possible for humans to be active at night time and allows us to work over a full 24-hour period. Factory workers operate heavy machinery, lorry drivers travel long distances, doctors have responsibility for patients’ lives, and air traffic controllers make fast decisions at times when their body clocks (circadian sleep-wake cycles) are completely out of synchronisation with the environment. It is therefore vital to understand the effect of working at night adn sleeping during the day on safety, productivity and health.
Light exposure can cause our biological clock to advance or delay, which affects our sleep and wake cycle.
Light is one of the most important external factors that can affect sleep. It doesn’t so both directly, by making it difficult for people to fall asleep, and indirectly, by influencing the timing of our internal clock and thereby affecting our preferred time to sleep.
Light influences our internal clock through specialised ‘light sensitive’ cells in the retina of our eyes.
due to teh invention of the electric light bulb in the late 19th century, people are now exposed to much more light at night than they have previously been exposed to throughout evolution.
Biological Approach: Factors Affecting Sleep - Environmental (Jet Lag and Shift Work)
Jet lag is caused by the body’s internal body clock being out of step with external cues. Individuals who travel across time zones or work night shift typically have two symptoms. One is insomnia when they are trying to sleep outside of their internal phase, and the other is excessive sleepiness during the time when their internal clock says that they should be asleep. (Circadian Sleep Disorder).
Biological Approach: Factors Affecting Sleep - Chemical Stimulants/ Depressants (Caffeine)
The most marked effects of caffeine on sleep, even at levels equivalent to those of single cup of coffee, have been well documented. They consist principally of prolonged sleep latency - going from fully wakefulness to sleep, shorter total sleep time, increases in light sleep and shortening of deep sleep time, as well as more frequent awakenings. REM sleep is less affected.
The effects depend not only on the amount of caffeine ingested at bedtime, but also on the amount of caffeine ingested over the whole day. Drake et al (2013) assessed the impact on sleep of caffeinne consumption at different times of day, suggesting that caffeine consumed up to 6hrs before sleep may have disruptive effects on sleep.
Biological Approach: Factors Affecting Sleep - Chemical Stimulants/ Depressants (Alcohol)
Alcohol is commonly used as a sleep aid. However, although alcohol can help a person fall asleep more quickly, the quality of that individual’s sleep under the influence of alcohol will be compromised. Ingesting more than one or two drinks shortly before bedtime has been shown to cause increased awakenings - and in some cases insomnia - due to the arousal effect the alcohol has it is metabolised later in the night.
Biological Approach: Sleep Hygiene
Sleep hygiene is nothing to do with whether you have a bath or shower before you go to the bed. Sleep hygiene is a variety of different practices that are necessary to have normal, quality night-time sleep and full daytime alterness. The most important sleep hygiene measure is to maintain a regular wake and sleep pattern seven days a week. It is also important to spend an appropriate amount of time in bed, not too little, or too excessive.
Sleep hygiene is important for everyone, from childhood through adulthood. A good sleep hygiene rountine promotes healthy sleep adn daytime alertness. Good sleep hygiene practises can prevent the development of sleep problems and disorders.
Sleep disturbances and daytime sleepiness are the most telling signs of poor sleep hygiene. If one is experiencing a sleep problem, he or she should evalute their sleep routine. It may take some time for the changes to have a positive effect.
If you’re taking too long to fall asleep, or awakening during the night, you should consider revising your bedtime habits. Most important for everyone is to maintain a regular sleep-wake schedule throughout the week and consider how much time you spend in bed, which could be too much or too little.
Biological Approach: Strengths
- Based on mature biological science.
- Looking at the chemical make-up of the brain has led to the successful production of a range of drug treatments in recent decades that have helped in the treatment of variety of issues.
- Biological approach is determinist and provides biological explanations about the biological causes of behaviour.
Biological Approach: Weaknesses
- Focuses just on biology; i.e. Nature, tending to ignore experience (Nurture) adn psychological factors, e.g. thoughts adn feelings. So, it is also a reductionist approach.
- The biological approach is nomthetic - i.e. looking to make generalisations about people by finding similarities and ignoring differences.
- Drugs only treat the biologically visible effects and not the causes of problems.
Biological Theories and Studies: Exposure to bright light and darkness to treat physiological maladaption to night work (Czeisler et al 1990)
Aim: To evaluate whether negative physical reactions to night time work could be prevented by treatment of exposure to bright light during the night and darkness during the day.
Method: 10 x 2 week studies were carried out on 8 men aged between 22 and 29 years. They had no medical or sleep disorders and none had worked shifts. The men were instructed to avoid alcohol or drugs. 5 control and 5 treatment studies were conducted. The temperature, physical activity and heart rate were recorded during a base week (normal activity). The participants then took part in a week of night shifts. In 2 conditions; in condition 1, the men were either exposed to bright light during the night shift adn told to remain in the dark at home between 09.00 and 17.00. In condition 2, participants were exposed to ordinary room light during the night shift and were given no instructions about staying in darkness durinng the day for any length of time. Participants completed hourly cognitive performance tasks and also assessments of their mood and alertness. They then went home after the night shifts.
Results: the men exposed to bright light at night and darkness during the day slept for 2 hours longer than the second group. The alertness of participants exposed to bright light was greater than before the use of bright light.
Conclusion: Exposure to a properly designed routine of light and dark induced a complete physiological adaption to night work. This has implications for industrial productivity and safety at work. Working in ordinary room light and then being exposed to bright daylight saw a failure of the circadian timing system to adapt. This was due to the biological effect of light.
Biological Theories and Studies: Exposure to Bright Light and Darkness to Treat Physiological Maladaption to Night Work (Czeisler et al 1990) - Evaluation
- All the participants were male therefore the results cannot be generalised.
- A small sample was used.
- Experimental method lacks ecological validity.
- Give some insight into the physiological effect of nnight working.
- Participants kept diaries at home which could be subjective adn inaccurate.
Biological Theories and Studies: Exposure to Bright Light and Darkness to Treat Physiological Maladaption to Night Work (Czeisler et al 1990) - Analysis
- The study highlighted the possible implications for industrial productivity and safety of people on night shift.
- It also highlighted the possible health consequences of sleep deprivation adn disruption of the circadian rhythm such as cardiovascular, digestive or sleep disorders.
- Further questions were posed from the study. What is more important in terms of dealing night working? Bright light at night or darkness during the day? Does age, gender play a role?
Biological Theories and Studies: Repair and Restoration Theory of Sleep (Oswald 1966)
This theory maintains that both REM and NREM sleep serve a restorative, replenshing function. NREM restores bodily processes that have been depleted. REM sleep is a time for replenishing and renewing brain processes - through stimulation of protein synthesis.
This theory accounts for the large proportion of babies’ sleeping time spent in REM sleep. During th efirst year babies sleep 18 out of 24 hours. By 12 months, they have 2 sleep periods every 24 hours (one daytime/ one night-time). Not until the age of 5 years is an adult circadian pattern established. This may be due to both environmental and maturational factors. The REM/ NREM pattern during this time shows that new born infants spen dhalf of the 18 hours in REM sleep. Adults spend one quarter of their 8 hours in REM sleep. The developing brain needs protein synthesis for cell manufacture and growth - REM sleep helps to achieve this.