What is sleep? Flashcards
Lecture 8
Define circadian rhythm
Circadian rhythms are physical, mental, and behavioral changes that follow a 24-hour cycle. This resets everyday by the sun’s light/dark cycle.
What is the wake maintenance zone?
This is a 2/3-hour phase prior to the evening onset of melatonin secretion where the circadian system maximally promotes wakefulness and performance.
What is melatonin?
A hormone your brain produces in response to darkness. This hormone is low throughout the day and rise at night.
What is free running sleep wake cycle/entrained cycle?
This is a rare sleep pattern whereby the sleep schedule of a person shifts later everyday.
Suprachiasmatic nucleus of the hypothalamus (SCN)
The suprachiasmatic nucleus (SCN) is a bilateral structure located in the anterior part of the hypothalamus. It is the central pacemaker of the circadian timing system and regulates most circadian rhythms in the body. This is the small part that controls your activity over 25hours.
What is the pineal gland and where is it located?
This pineal gland releases the hormone melatonin at night. It is located in the center of the brain.
What is zeitgeber?
This is the thing that keeps your body in the right hours and periods of light. Your internal clock can only shift about an hour a day for humans. Light controls the body clock by activating the suprachiasmatic nucleas.
Define Melanopsin receptors.
Melanopsin, a G family coupled receptor, found within the ganglion cell layer in the retina, plays an important role in non-image-forming visual functions, including hormone secretion, entrainment of circadian rhythms, cognitive and affective processes.
Phase delay vs phase advance
A phase shift in your circadian rhythms means that your bedtime and wake up time will move earlier in the day (phase advance) or later in the day (phase delay.)
What is the core function of sleep?
The core function of sleep is to adapt people to their specific environment niche. There are many theories including the inactivity theory, energy conservation theory and repair explanations of sleep.
Explain the inactivity theory of sleep.
This theory states that sleep forces us to remain quiet during periods of vulnerability. This theory makes sense but, it is always safer to remain conscious in order to be able to react to an emergency.
Explain the energy conservation theory.
This theory states that sleep focuses us to conserve energy at times when we would be relatively inefficient at searching for food. Energy metabolism is reduced by 10% during sleep in humans- decreased body temperature and caloric demand.
What is recuperation/ repair explanations of sleep?
Sleep deprivation should produce physiological and psychological disturbances. These disturbances should get worse as deprivation continuous. After deprivation much of the sleep debt will be recovered.
Who was the men that didn’t sleep?
Peter Tripp and Randy Gardener.
Why is sleep important for brain recovery and muscles repair?
Muscle growth, tissue repair, protein synthesis and growth hormone release occur mostly during sleep.
