My psychology sleep and dreams flashcards

What are circadian rhythms?

Body rhythms that occur over a 24 hour cycle.

Example of a circadian rhythm

Sleep

Biological clock

We have a biological clock which is used to anticipate the differing demands of the 24 hour day, ensuring we are ready for these demands.

What happens in anticipation of going to bed?

Body temperature drops, blood pressure decreases, cognitive performance declines and tiredness increases.

What happens before dawn?

Metabolism is geared up in anticipation of increased activity when we wake.

Endogenous (internal) pacemaker

The internal biological clock (circadian rhythm)

Exogenous pacemakers

External cues from the environment eg light which tell the body it is time to sleep.

Endogenous (internal) sleep relating substances

E.g. Adenosine

Who conducted a cave study in 1962?

Michel Siffre

How long did Michel Siffre live in total isolation during his cave study?

Two months

What did Michel Siffre lack during his cave study?

Clocks or light to mark daytime

What did Michel Siffre do every time he woke up, ate, and went back to sleep?

He telephoned his research assistants

What was the initial sleep pattern of Michel Siffre during his cave study?

Very erratic sleep patterns

What sleep/wake cycle did Michel Siffre settle into during his cave study?

Roughly 24-25 hours

Two key brain structures that control circadian rhythms

Suprachiasmatic nucleus (SCN) and the pineal gland

What is the role of the suprachiasmatic nucleus (SCN)?

The SCN controls the sleep-wake cycle.

What is the suprachiasmatic nucleus (SCN) often referred to as?

Our 'internal biological clock'.

What type of rhythm does the SCN have?

An endogenous circadian rhythm.

What did Stephen and Zucker (1972) do to lab rats?

They destroyed the SCN of lab rats.

What was the effect of destroying the SCN in lab rats?

The rats lost their normal circadian rhythm.

What behavioral disruptions did the lab rats experience after SCN destruction?

They showed disrupted sleep-wake cycles and feeding times.

Did environmental cues still influence the behavior of lab rats after SCN destruction?

Yes, environmental cues such as light still influenced behavior to some extent.

What happened to the behavior of lab rats without their SCN?

They became disorganized.

What is the role of the retina in relation to the SCN?

The retina of the eye is connected to the SCN via a nerve pathway.

What does the SCN signal to the pineal gland?

The SCN sends signals to the pineal gland telling it if it is light or dark.

What happens to melatonin production when it is light?

The pineal gland produces less melatonin.

What happens to melatonin production when it is dark?

The pineal gland produces more melatonin.

Melatonin

The sleep hormone. High levels of it stimulate sleep.

What did Zhdanova et al (1995) examine?

The effect of melatonin supplements on how quickly people fell asleep.

What was the finding of Zhdanova et al (1995) regarding low doses of melatonin?

Low doses of melatonin supplements administered in the evening could reduce the time it takes to fall asleep.

Who were the participants in the Zhdanova et al (1995) study?

Both young and elderly participants.

What builds up in our cerebrospinal fluid during waking hours?

Adenosine

What effect does the accumulation of adenosine have?

It increases the pressure to sleep.

How is sleep pressure released?

By the act of sleeping.

What clears adenosine from the body?

Sleeping

What replaces adenosine after sleep?

Glycogen

What does glycogen provide us with?

Energy

What was the aim of the study by Porkka-Heiskanen et al (1997)?

To find out if there was a direct relationship between adenosine and wakefulness.

What was the sleep-wake pattern of the control group in the Porkka-Heiskanen et al (1997) study?

The control group of rats had a normal sleep-wake pattern.

What happened to the other group of rats in the Porkka-Heiskanen et al (1997) study?

They were kept awake for several hours.

What did researchers measure in the rats during the Porkka-Heiskanen et al (1997) study?

The adenosine levels of the rats.

What was the finding regarding adenosine levels during wakefulness in the Porkka-Heiskanen et al (1997) study?

Adenosine increased during periods of being awake.

What was observed about adenosine levels the longer the rats were awake in the Porkka-Heiskanen et al (1997) study?

The longer they were awake, the more adenosine was created.

What happened to adenosine levels when the rats slept in the Porkka-Heiskanen et al (1997) study?

Adenosine dropped significantly.

Environmental factors - light

Ideally a person should not be exposed to any light when sleeping. Light especially 'blue' light from electronic devices mimics daylight and tricks the pineal gland into reducing melatonin.

What type of drug is caffeine?

Caffeine is a stimulant drug.

How does caffeine affect sleep?

Caffeine can make it much more difficult to fall asleep if ingested.

What neurotransmitter does caffeine affect?

Caffeine affects adenosine.

How does caffeine interact with adenosine receptors?

Caffeine blocks adenosine receptors.

What is the result of caffeine blocking adenosine receptors?

It makes the body less reactive to adenosine build-up, which stops us from feeling tired.

Drake et al (2013)

Assessed the impact on sleep of caffeine consumption at different times of day, suggesting that caffeine consumed up to 6 hours before sleep may have disruptive effects on sleep.

What type of effect does alcohol have on sleep?

Alcohol is a soporific, which means it encourages sleep.

How does alcohol affect the quality of sleep?

The quality of sleep under the influence of alcohol is compromised.

What effect does alcohol have on REM sleep?

Alcohol reduces the amount of REM sleep an individual will have.

How do individuals typically feel the morning after consuming alcohol?

Individuals often wake up feeling groggy and generally 'rough'.

What is Stage 1 of sleep?

The person is not fully awake nor fully asleep.

What characterizes Stage 1 of sleep?

It is characterized by head-nodding if sitting up and an overwhelming desire to shut your eyes.

What happens to the eyes during Stage 1 of sleep?

The eyes begin to roll in your head.

What common sensation may occur during Stage 1 of sleep?

A feeling of falling is common.

What is the hypnogogic jerk?

It is a twitch or jerk that can occur during Stage 1 of sleep.

How long does Stage 1 of sleep last?

It lasts around 10 minutes.

What percentage of total sleep does Stage 1 account for?

Stage 1 accounts for 4-5% of our total night's sleep.

What is Stage 2 of sleep?

Light, dreamless sleep.

What happens to a person's muscles during Stage 2 of sleep?

The person's muscles relax.

What happens to the brain during Stage 2 of sleep?

The brain slows.

What may develop if throat and tongue muscles relax too much during Stage 2 of sleep?

Snoring.

How long does Stage 2 of sleep last?

Approximately 20 minutes.

What percentage of our total night's sleep does Stage 2 account for?

45-55%.

Stage 3 of sleep

This is heavier but still dreamless sleep. Lasts approximately 15 minutes. Accounts for 4-6% of our total nights sleep.

Stage 4 of sleep

This is very heavy sleep. Skeletal muscles are slowly switched off meaning movement is difficult. If woken the person is likely to be extremely groggy and confused. Lasts for approximately 30 minutes. Accounts for 12-15% of our total nights sleep.

What stage of sleep should we ideally wake up in?

Stage 1 or 2 at a push as your brain will be practically awake.

What happens if you wake up in stage 3 or 4?

You will be groggy and grumpy all day.

What type of sleep is stages 1-4?

nREM

What type of sleep is stage 5?

REM

What stage of sleep is characterized by very deep sleep?

Stage 5 of sleep

What happens to a person's muscles during Stage 5 of sleep?

They are essentially paralysed.

Is it easy or difficult to wake someone in Stage 5 of sleep?

It is almost impossible to wake them.

What is the activity level of the brain during Stage 5 of sleep?

The brain is very active.

Rechtstaffen (1983)

Studied pairs of rats. One of the pair was allowed to sleep normally whilst the other would be forced to stay awake. If it slept it would be plunged into a pool of water. All the rats subjected to total sleep deprivation died between 11 and 23 days.

Who developed the Restoration theory?

Ian Oswald

In what year was the Restoration theory developed?

1966

What is the primary purpose of sleep according to the Restoration theory?

To repair cells, restore energy, and allow growth to occur.

What type of sleep is important for restoring physiological functions?

nREM sleep

What type of sleep is essential for restoring mental functions?

REM sleep

Restoration functions

Repairing minor injuries such as skin or muscle. Removal of waste chemicals in the muscle. Repleneshing neurotransmitters and/or energy in the brain.

Strengths of the restoration theory

It is a logical explanation of why all animals need sleep and it is clear that lack of sleep results in poorer performance.

Weakness of the restoration theory

Evidence seems to be growing that sleep is more important to restoration of the brain than the body but the debate isn't fully resolved.

Czeisler et al (1990) aim

To find out whether disturbances in the sleep-wake cycle created by working at night could be prevented by a treatment program of exposure to bright light during the night and darkness during the day.

Czeisler et al (1990) participants

8 men between the ages of 22-29 years old

Czeisler et al (1990) type of experiment

Lab experiment

Czeisler et al (1990) groups

Five control and five treatment studies conducted in all.

Czeisler et al (1990) procedure

In both versions participants would report for work at a lab and would complete cognitive-performance tasks between midnight and 8 am.

Czeisler et al (1990) lighting

The control group had ordinary room lighting. The treatment group had bright lights.

Czeisler et al (1990) results

In short the treatment group had successfully adapted their circadian-rhythms to the night time work schedule whereas the control group had not. They continued to experience the sleep part at night whilst working.

Czeisler et al (1990) strengths

Easy to replicate, lab experiment

Czeisler et al (1990) weaknesses

Lacks ecological validity and only used males

Acquisition

The introduction of new information into the brain

Consolidation

The processes by which a memory becomes stable and permanent.

Recall

The ability to access the information while consciously or unconciously after it has been stored.

When do acquisition and recall occur?

Only when we are awake.