A2 Psychology

Circadian Rhythms

A circadian rhythm repeats in a cycle of once every 24 hours. Mammals possess about 100 circadian rhythms. The 24-hour sleep–waking cycle is a good example of a circadian rhythm because it clearly illustrates that circadian rhythms depend on an interaction of physiological and psychological processes. Our fairly consistent sleep pattern suggests an internal or endogenous mechanism—the biological clock. But this can be overridden by psychological factors such as anxiety.

Infradian Rhythms

An Infradian rhythm involves a cycle greater than 24 hours. For example, the human menstrual cycle occurs every 28 days, although it can be 20–60 days. It is controlled by the hormones oestrogen and progesterone (ovarian hormones), and the target organs are the ovaries and womb. The hormones cause the release of the egg and thickening of the lining of the womb so that it is ready to receive a fertilised egg. If the egg is not fertilised the lining is shed and so menstruation is the outcome of a cycle of activity that prepares the body for conception. Menstruation is an endogenous mechanism as it is controlled mainly by internal biological factors (the hormones) but exogenous factors (external cues) can also affect the rhythm.

The sleep–wake cycle, offers important insights into the nature of sleep such as the role of the biological clocks, the SCN and the pineal gland, and the role of biochemicals such as the melatonin released by the pineal gland when it receives electrical messages from the SCN that the light level is low. Melatonin influences the production of serotonin and this accumulates in the raphe nuclei in the hindbrain, near the pons, and stimulates the shutting down of the RAS (reticular activating system), which is closely linked with brain activity. So serotonin could be the switch to start sleep.

Jouvet (1967) has also identified noradrenaline as a biochemical affecting sleep. Noradrenaline accumulates in the locus coeruleus in the pons and if this area is damaged, noradrenaline levels fall and REM sleep is impaired. This led him to conclude that different areas of the brain and the corresponding neurotransmitters controlled the two types of sleep, NREM and REM. The raphe nuclei and its serotonin pathway controls NREM sleep; the locus coeruleus and noradrenaline pathway control REM sleep.

However, the circuitry involved is more complex than Jouvet suggests as the pons, raphe nuclei, and locus coeruleus (among others) are involved in sleep, along with a number of different neurotransmitters, especially serotonin, noradrenaline, and acetylcholine. Supporting evidence comes from links to other brain areas, and also shows that the relationships between brain areas and sleep may not be clear-cut as damage to the locus coeruleus or its pathways does not affect REM sleep.

Insomnia can be categorised as primary or secondary insomnia depending on the cause. Primary insomnia is the most common form of insomnia and has no clear underlying cause. There is a sleep problem, but there is no physiological or psychiatric cause, and it is likely that the sleep problem is the result of maladaptive behaviour or learning. The clinical characteristics are that the individual has suffered from insomnia for at least a month but this would not be linked with any other sleep disorder, such as parasomnia or narcolepsy, nor with another psychopathology such as clinical depression, nor with medications or substance abuse. Worrying about the insomnia can lead to a cycle that is hard to break because the more a person focuses on their sleep problems the less likely they are to get good quality sleep.

Secondary insomnia is insomnia that has a specific cause. Examples of such causes include sleep apnoea, restless legs syndrome (RLS), circadian rhythm disorders due to night shift work, and various medical, substance use, and emotional problems.

Stress

Acute stress, perhaps from a major life event such as an exam or a job change, can lead to insomnia, again because brain activity is heightened, the sympathetic ANS is active, and so the parasympathetic ANS cannot switch. Acute stress is transitory and so when it is over normal sleep should resume. However, with chronic stress the stressor persists, and so sympathetic ANS activity remains high, which can lead to long-term disrupted sleep.

Sleep Hygiene/Bedtime Behaviour

Sleep hygiene refers to the habits and bedtime behaviour patterns that promote the calming and slowing down of the brain in preparation for sleep. Poor sleep hygiene refers to habits that do not promote this progression: consuming caffeine or alcohol or taking in nicotine interfere with brain activity and the sleep process. Similarly stimulating activities, particularly if these take place in the bedroom, such as watching TV, chatting on the phone, or doing homework can also lead to insomnia. A delayed bedtime for whatever reason—more stories, more TV, a drink—also delays settling down ready for sleep. Night fears, e.g. of the dark, also prevent the calming down needed for sleep. Poor sleep hygiene means the brain is very active, it is still alert and in daytime mode, and so the parasympathetic ANS (autonomic nervous system), the rest-and-digest mechanism, will not switch on and calm the brain, and insomnia is the result. Taking naps during the day is another aspect of sleep hygiene that can perpetuate insomnia.

Social Exchange Theory (SET)

The basic assumptions of social exchange theory (SET) are that relationships provide both rewards (e.g. affection, sex, emotional support) and costs (e.g. providing support, not always having your own way). Everyone tries to maximise rewards while minimising costs. Thibaut and Kelley (1959, see A2 Level Psychology page 118) argued that long-term friendships and relationships go through four stages: sampling, bargaining, negotiation, and institutionalisation, when rewards and costs are established and entrenched. How satisfied individuals are with the rewards and costs of a relationship will depend on what they have come to expect from previous relationships. In other words, they have a comparison level (CL) (Thibaut & Kelley, 1959), representing the outcomes they believe they deserve on the basis of past experiences—so if in the past they have had very poor relationships they may expect very little from subsequent ones. In addition, their level of satisfaction will depend on the rewards and costs that would be involved if they formed a relationship with someone else; this is known as the “comparison level for alternatives” (CLalt). All of this makes sense—if you are a very attractive and popular person, you can afford to be very choosy in your friendships and relationships.

Economic Theories: Equity Theory

Equity theory is an extension of social exchange theory. The basic assumption is that people only consider a relationship to be satisfactory if what they gain from it reflects what they give to it. This means that if one person contributes more, they feel they should get more out of it. Equity is especially important at the beginning of a relationship rather than when it is firmly established. Walster, Walster, and Berscheid (1978, see A2 Level Psychology page 120) expressed key assumptions of equity theory, such as: individuals try to maximise the rewards they receive and minimise the costs; there is negotiation to produce fairness; distress and relationship breakdown may follow when the relationship is unfair or inequitable.

Gender dysphoria (also known as gender identity disorder) is a condition in which people are uncomfortable with the gender to which they have been assigned (dysphoria means unhappiness). In the extreme, this can lead to transsexualism, a desire to change your gender. Most people are happy with the gender in which they have been reared but in a few cases individuals do not feel that they have been assigned the correct gender. Some girls feel as if they should be a boy and conversely, some boys feel that they are a girl. This is more common in boys but occurs in both sexes.

The biological explanation: the influence of prenatal hormones. Girls have sex chromosomes known as ** whilst boys have sex chromosomes known as XY. One explanation of gender dysphoria is that it is caused by unusual development in parts of the brain before birth. There are small areas of the brain that are different in males and females. The theory is that in people experiencing gender dysphoria one of these areas has developed in a way that corresponds to the opposite sex of their other biological sex characteristics. It is possible that hormones can cause parts of the brain to develop in a way that is not consistent with the genitalia and, usually, with the chromosomes. This means that the brain has not developed in a way that corresponds to the gender assigned to the child at birth.

Family constellations. Stoller (1968, see A2 Level Psychology page 241) points out that certain family conditions are associated with gender dysphoria. For boys who want to be girls, he suggests that there is an over-close relationship with the mother and a distant father. For girls who want to be boys, he suggests that that they have a depressed mother in the first few months of their life and a father who is either not present or does not support the mother but leaves the child to try to control the mother’s depression.

Rekers links gender dysphoria in boys to absence of a father figure, either physically or psychologically.

Up to about the age of 8–10, negligible amounts of sex hormones are produced by either sex but after that both sexes produce more male and female hormones. From around 11 years of age, both girls and boys increase their production of female hormones but females produce far more than boys. Conversely, once children reach puberty both sexes increases their production of male sex hormones rapidly but boys more so than girls.