Introduction to altered states of consciousness: wakefulness and sleep
How healthy are your sleep habits? https://www.psychologytoday.com/us/tests/health/sleep-habits-test
Importance of circadian rhytms(Van Drunen & Eckel-Mahan, 2023)
Oscilations
Oscillations constitute a universal phenomenon, across biological systems (Dang-Vu, 2020)
The oscillatory nature of biological processes results from complex coordinated interactions, which may confer functional advantages in performing physiological functions and maintaining homeostasis.
In the central nervous system, oscillations reflect fundamental properties of neuronal activity.
Increasing evidence shows that behaviours, cognition, mood, and vigilance states are governed by specific patterns of neuronal oscillations
Dreaming is the most commonly occurring altered state of consciousness (ASC) (Revonsuo, 2017)
Not All Sleep Is Restorative
Restorative theory
Sleep allows for the body to repair and replete cellular components necessary for biological functions that become depleted throughout an awake day (Brinkman, 2023. Physiology of Sleep).
Muscle repair, tissue growth, protein synthesis, and release of many of the important hormones for growth occur primarily during sleep.
Brain plasticity theory: sleep is necessary for neural reorganization and growth of the brain’s structure and function.
Sleep plays a role in the development of the brain in infants and children and explains why infants must sleep upwards of 14 hours per day.
How to improve restorative sleep
- Maintain a consistent schedule: Go to bed and wake up around the same time every day.
- Optimize your environment: Make sure your bedroom is cool, dark, and quiet.
- Limit certain substances: Avoid caffeine for 6-8 hours before bed and alcohol (both disrupt sleep quality).
- Exercise regularly but avoid high-intensity workouts close to bedtime.
- Manage stress: Try to resolve worries before bed.
- Rule Out Obstructive Sleep Apnea
Dream and consciousness
Sleep - definition
Sleep may be defined as a physiological state of unconsciousness that is reversible, cognitive and perceptual disengagement from and to the environment are seen during this temporary unconsciousness, and from which the arousal is possible in response to any internal or external stimuli (Gupta et al., 2018)
Neurobiology of sleep
Sleep is dependent upon two processes:
- homeostatic
- circardian
The homeostatic
- also known as S process
- feel sleepy depending upon the duration of wakefulness
- the longer the period of wakefulness, the higher the proportion of deep sleep
The homeostatic neurobiology
Depends upon two major areas of the brain that are located near the hypothalamus:
- sleep-promoting area – the ventrolateral preoptic nucleus (VLPO), which sends inhibitory signals through the GABAergic neurons to the wake-promoting area of the brain.
- Wakefulness is dependent upon the monoaminergic nuclei of the brain that are the part of the reticular activating system (RAS).
Hypocretin neurons
The activity of both wake-promoting and sleep-promoting areas is modulated through another group of neurons - the hypocretin neurons that are present in the lateral and posterior hypothalamus.
The hypocretin neurons modulate the activity of the other two areas of the brain in such a manner that only one state of consciousness, that is, wakefulness or sleep
Damage to the hypocretin neurons leads to a condition known as narcolepsy.
Hypocretin neurons
The circadian process
- also known as C process
- dependent upon environmental light
- other factors can also regulate this process, for example, food, emotions, social activity, and exercise.
- These factors are called zeitgebers
- Light is the strongest factor which can entrain the cir- cadian rhythm.