1 / 7

Theories of sleep

Theories of sleep. Hibernation theory (Webb, 1974) Evolutionary approach – sleep is assumed to confer a survival advantage Sleep helps conserve energy by: Reducing energy spent on behavioural activity Drop in body temp & metabolic rate reduces energy lost as heat. psychlotron.org.uk.

iphigenie
Download Presentation

Theories of sleep

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Theories of sleep • Hibernation theory (Webb, 1974) • Evolutionary approach – sleep is assumed to confer a survival advantage • Sleep helps conserve energy by: • Reducing energy spent on behavioural activity • Drop in body temp & metabolic rate reduces energy lost as heat psychlotron.org.uk

  2. Hibernation theory • Main prediction is that an animal’s sleep pattern will be determined by its energy intake & expenditure pattern • Small animals will need more than large • Diet (e.g. carnivore vs. herbivore) will affect sleep patterns • Sleep will increase when energy loss goes up (cold) or energy intake goes down (food scarcity) psychlotron.org.uk

  3. Animal sleep patterns Sleep patterns vary by species 3hrs 4hrs 8hrs 16hrs 20hrs psychlotron.org.uk less more

  4. Evidence • Comparative studies of different species generally support evolutionary view • Smaller animals tend to sleep more than larger (e.g. giraffe 1hr vs. bat 20hrs) • Carnivores sleep more than herbivores (e.g. lion 16hrs vs. buffalo 3hrs) • Some notable exceptions e.g. rabbit (small, herbivore) & human (much larger, omnivore) both sleep about 8hrs psychlotron.org.uk

  5. Evidence • Sleep patterns are affected by energy expenditure & availability • Animals generally sleep more when weather is cold and food is scarce (Berger & Phillips, 1995) • However, no direct correlation between physical work done and sleep duration in humans (e.g. Horne & Minard, 1985) psychlotron.org.uk

  6. Problems • Many evolutionary significant factors could affect sleep patterns; theory doesn’t tell us which are important • Does a bat get so much sleep because it’s small or because it has few predators? • Why do animals with very different lifestyles have similar sleep patterns? psychlotron.org.uk

  7. Problems • Some features of sleep cannot be explained easily by the hibernation theory: • Why is sleep universal when in some species (e.g. dolphins) it would have been an advantage to get rid of it? • Why is sleep deprivation apparently fatal? psychlotron.org.uk

More Related