Psychological: Sleep

The Nature of Sleep

Function/theories of Sleep

Lifespan Changes in Sleep

  • Created by: Chloe
  • Created on: 11-12-11 15:50


Sleep wake cycle is a Circadian rhythms (once a day). Sleep is a repetitive cycle of stages lasting 90 mins and this is a Ultradian rhythm (more then one a day) .

EEG: measures brain activity - determine if awake or sleep

EOG: measures eye movement - informs when dreaming and in REM stage 

EMG: measures muscle activity                                   


 M = muscle

O = nerve in eye

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A01: Stages of Sleep (1-4 and REM)

Stage 1 and 2 (NREM) - Funcation for psysical rest

Brain waves - small, slow and irregular 

Decrease - blood pressure, body temperature and heart rate

Stage 3 and 4 (NREM_- Funcation for physical rest

Brain waves - slow and large

Deepest physical rest - difficult to awake (confused, groggy)

Rem - (rapid eye movement sleep) Funcation for brain recovery

Increase heart rate, blood pressure fluctuates                  Periods of dreams

EOG (active)                                                                EMG (inactive)

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Lifespan Changes in Sleep: Toddlers

Infants sleep around 13 hour each day. Infants REM decreased 4 to 5 hours.2 to 3 years olds still commonly have daytime naps

Research into factors that may impact on sleep patterns - Maternal behaviour

  Infants born full time, 11 to depressed mothers and infants studied at 6 months. Infants born to depressed mothers had different sleep patterns and took longer to fall asleep, compared to control group.

Adolescents need more sleep during this important period of development. Sleep in adolescents can be disrupted due to hormones changes in the body. Therefore this can cause adolescents to have symptoms like moodiness and lack of motivation.

Research: Phase delay

Adolescents’ Circadian rhythms change, so that they stay up later, and wake up later. Researchers suggest that school day is adjusted so that delayed sleep phase syndrome is prevented. Delayed sleep phase syndrome causes poor attention span in the morning

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A02/A03 Commentary

Methodological problems

Research conducted on sleep involves participants to sleep in laboratories and to be connected to many electrodes around their head. The participants are in an unknown/artificial environment which must have some effect on quality and quantity of sleep that participants experience. Researches have managed to overcome this methodological problem by asking participants to sleep in the laboratory for more than one night. 

Measurements of sleep

Measuring dreaming using self-reports methods, like questionnaires have high demand characteristic and social desirability bias. This can result in the finding of the study to be incorrect and not valid. The results of the questionnaires use participant’s opinions and are therefore subjective.

Sleep objectively measured using scientific equipment like EEG, EOG and EMG. This means that researches are able to check for internal reliability.  

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Nature of Sleep Research

Dement and Klietman - dreams recalled

Monitoring EEG recording, they awaked participants in the different stages of sleep and asked them to report how feeling and emotions experience. Participants awaked in REM sleep reported detail images (80-90%). Participants awaked in NREM sleep only recalled dream around 7% of the time.

Other Research - ability to influence dreams

Researchers suggested that we can influence participants dream. They sprayed water on participants. Research showed that the participants were more likely to report that their dream had water theme compared to controlled group.

Other Research - reporting dreams

70% of dreams can happen in NREM. It is difficult to define what a dream is. Participants may have experiences muddled through which they think is a dream, they can become confused and therefore stated something that is incorrect.

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A02/A03 Commentary and IDA

Objective measurements

Research into lifespan changes in sleep has been conducted in sleep laboratories around the world, and the changes noted in the different stages of sleep involving both the quantity and the quality of sleep have been replicated and are reasonably well established.


Reductionism: explaining life changes and nature of sleep only uses the biological approach and scientific methods to provide - bodily process - hormones in adolescent and change in Circadian rhythms - delayed sleep phase syndrome

The Nature/Nurture: biological need for sleep in order to function, however exogenous zeitgebers and external factors, e.g. lack of parental influence, social pressures determine when we go to sleep. Combined of the Nature and Nurture.

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