14.8 - Effects of long term sleep reduction

Question 1

what are the two interpretations of the fact that there are significant negative symptoms associated with getting less sleep than normal?

Answer 1

1. indicate that we need to sleep our average amount
2. brain needs a small ammt of sleep, but will sleep more under ideal conditions because of its positive incentive value
   - brain adapts to the amount of sleep it gets, even if its far more than needed, and disturbed when there is a reduction

Question 2

how do we determine if we need the amount of sleep we get or if we have only adjusted to the amount of sleep

Answer 2

study individuals who sleep little, either bc they have always done so or they reduced their sleep times purposefully

• if ppl need 8 hours/night, short sleepers should be suffering from health and performance problems
• if not, they should be fine

Question 3

what are the three strong features of the fichten and colleagues study of short vs long sleepers?

Answer 3

1. large sample of short and long sleepers (239)
2. compared them in terms of 48 measures, including sleepiness, naps, regularity of sleep times, business, meal times, stress, anxiety, depression, life saisfactio and worrying
3. screened out volunteers who were ill or under stress or pressure

Question 4

what did the fichten and colleagues study of short vs long sleepers find?

Answer 4

absolutely no differences other than the amount of time slept - only studies that failed to screen out negative characteristics in short sleeping groups found negative outcomes of short sleep

Question 5

explain the Webb and Agnew study on long term sleep reduction

Answer 5

16 volunteers slept for only 5.5 hours a night for 2 months, only detectible deficit was in vigilance

Question 6

Explain the Fridman/Mullaney study on long term sleep reduction

Answer 6

8 volunteers reduced their nightly sleep by 30 mins every 2 weeks until they reached 6.5 hours, then by 30 minutes every 3 weeks until 5 hours, then 30 mins every 4 weeks after

• when a participant said they would not like to decrease sleep anymore, they spend 1 month sleeping their shortest duration
• then added 30 mins to this and held there for a year

Question 7

explain the findings of the Friedman/Mullaney study on gradual sleep reduction? (general plus 7 specifics)

Answer 7

minimum duration of nightly sleep was between 4.5 and 5.5 hours

• reduction of sleep was associated with
  1. increase efficiency of sleep
  2. decrease the ammt of time to fall asleep in bed
  3. decrease the number of nightime awakenings
  4. increase in proportion fo slow wave sleep
  5. day time sleepiness after 6 hours or less
  6. no deficits on any mode medical or performance tests
  7. at a 1 year follow ppl after the end of the study, participants were sleeping between 7 and 18 hours less per week than when they started

Question 8

what types of animals display polyphasic sleep cycles?

Answer 8

most mammals and human infants

Question 9

what types of animals display monophonic sleep cycles?

Answer 9

adult humans

Question 10

do adult humans experience purely monophhasic sleep cycles in terms of sleepiness?

Answer 10

no, they do display polyphasic cycles of sleepiness, periods of sleepiness during late afternoon and morning

Question 11

which is more efficient, monophonic or polyphascic sleep cycles?

Answer 11

polyphasic, out of proportion to its brevity

Question 12

what stimulated interest in polyphasic sleep cycles?

Answer 12

Davinci, who slept an average of 1.5 hours a day by applying for 15 minutes every 4 Hours

Question 13

what are the main findings of polyphasic sleep studies?

Answer 13

1. takes several weeks to adapt to the schedule
2. once adapted, participants were content and displayed no deficits onperformance tests
3. 4 hour schedule worked well, but in unstructured works situations individuals tend to vary the duration of the cycle without any negative consequences
4. most people display a preference for a particular sleep duration, and refrain from sleeping to little (unrefreshed) or too much (groggy)
5. most sleep becomes slow wave sleep when they first adopt the schedule, but then returned to a mix of REM and slow wave

Question 14

what is sleep inertia

Answer 14

The unpleasant feeling of grogginess sometimes experienced for a few minutes after waking

Question 15

what demolished the belief that 8 hours plus per night is ideal for health?

Answer 15

a series of large scale epidemiological studies conducted in th US and Japan, which did not include participants who were a potential source of bias (ill, depressed, under stress)

Question 16

what were the results of a meta analysis of the epidemic,iological studies on sleep duration?

Answer 16

1. fewest deaths associated with those sleeping 5-7 hours, (not causal, just a correlation)
2. any findings that less sleep is associated with illness is likely due to confounds

Question 17

how long do people in preindustrial societies tend to sleep?

are they often ill?

Answer 17

5. 7-7.1 hours

- nope, they have higher levels of fitness than people in industrial societies!