Sleep is a state of diminished mental and visceral function where awareness of peripheral senses is changed and some degree of sensory perception is blocked. There is a <sleep= stage in which muscular activity is slackened and there is minimal interaction with the environment as well. While sleep differs from wakefulness in regard to responding towards stimuli, there remains to be a functional brain activity underlying sleep, thereby rendering it more advanced than a state of coma or other consciousness controlling disorders.
Sleep Cycles
REM Sleep
Non-REM Sleep
Awakening
Transition
Sleep occurs in repeating periods during which the body alternates between two states: REM and non-REM sleep. Though REM stands for “rapid eye movement”, this sleep has many other features, including virtual body paralysis. Alternating NREM and REM sleep lasts about 90 minutes per cycle, repeating 436 times during a good night’s sleep.
Physiology of Sleep
Brain Activity
The brain uses significantly less energy during sleep than it does when awake, especially during non-REM sleep. In areas with reduced activity, the brain restores its supply of adenosine triphosphate (ATP), the molecule used for short-term storage and transport of energy.
Beta (13 – 30 Hz) > Present in REM sleep or wakefulness and can be seen as faster, low amplitude waves. Show active brain processing
Alpha (8-13 Hz) > Most frequent during relaxed wakefulness, elevated in early stages of sleep.
Theta (4-8 Hz) > Deeper in Non-REM sleep theta waves have a higher occurrence. Theta is also associated with REM and dreaming.
Delta (0.5-5 Hz) > Slower, higher amplitude waves. Body restoration, muscle repairing, immunity production.
Brain Activity Explained DEEPER!
While we may just be “sleep” the brain and body go through many processes in keeping up maintenance on our systems. We consolidate our memories when we sleep forming short term into long term memories through a process that signals from the hippocampus called hippocampal replay.
Glymphatic system is responsible for the removal of waste and toxins while we sleep. Using Cerebral spinal fluid to wash these toxins from our brain. Helping aid in the removals of metabolic waste, rhythmic waves will flow cerebral spinal fluid out. Sleep is essential in the process of neuroplasticity which allows us to improve and adapt through life. Strengthening old neurons and forming new ones/interconnections. Sleep Spindles (11-16 Hz) > Shot burst in N2 of sleep, and are beneficial to memory consolidation.
Hormone Secretion
There are several hormones that are produced, released, and secreted while we sleep.
Melatonin > This is released in order to prepare and signal to sleep. In many people it is known that melatonin is at its peak production at times from 2:00 am – 4:00 am. However, in many of ours patients we see this being different due to neurological and physiological conditions. Melatonin helps to regulate our circadian rhythm, this process is to help ensure we are resting and waking within the time frames we are supposed to with relaxation or energy needed to sleep or wake up. Melatonin > Interacts with the suprachiasmatic nucleus > Regulator of sleep/wake cycles. Melatonin Receptors > MT1 & MT2 ( G Protein coupled receptors)
Cortisol > Produced by the adrenal glands, cortisol is a steroid that helps to regulate other hormones in the body. Known as the stress hormone, cortisol is used throughout the day and released in pulses but is typically at a peak in the morning 30 minutes after waking. The HPA Axis regulates cortisol, and cortisol levels can be disrupted by many things including stress, lack of sleep, even excessive light during night time. Cortisol is typically supposed to be at its highest from 6:00 am – 8:00 am. Cortisol dysregulation can lead to metabolic health concerns.
Growth Hormone (GH) > Essential for restoration and repair, and muscle recovery. HGH is released in deep slow wave sleep. If there is not adequate sleep or there is issues related to sleep their may be growth hormone deficiency (GHD).
Heart Physiology
Sleep Disorders
- Insomnia
Difficulty falling asleep or staying asleep
Hyperarousal > Stemming from elevated metabolic rate, increase in brain activity, and in a QEEG/EEG we would see this as heightened beta waves while trying to sleep. HPA Dysfunction > Stress hormone regulator dysfunction which can lead to that hyperarousal. Imbalance of Neurotransmitters > Norepinephrine and epinephrine released in uneven amounts or no balance between the two. Disruption to the circadian rhythm, staying up through the night till the birds are chirping and sun it out. Stress, anxiety, and other emotions that may keep you looming through your thoughts in the late night! Life can be stressful, need to find the additional time before bed to mechanically and physiologically rest and reset.
2. Sleep Apnea
Pauses in breathing during sleep/obstructed breathing.
Reduced > Hypopneas Pauses > Apneas Upper airway collapse during sleep is known as the most common and is > OSA The misconnect between the brain and breathing muscles > Central Sleep Apnea or CSA > CSA is considered more dangerous than other apneas and usually stems from more underlying medical conditions, like neurological disorders, brain trauma, etc.
3. Narcolepsy
The brain inability to control sleep/wake cycle.
In many cases of narcolepsy the bodies immune system will attack the hypothalamus by accident, destroying neurons. Leading to a > Hypocretin Deficiency Loss in Hypocretin leads to the cause of involuntary REM from lack in control of sleep/wake. Excessive daytime sleepiness > EDS Cataplexy > Strong emotions can trigger you to fall into sleep paralysis. (Laughter, anger etc.)
4. Restless Leg Syndrome
Uncomfortable sensations in the legs and an urge to move them
In short its several factors that can contribute to (RLS). Dopamine Dysregulation > Basal Ganglia is responsible for movement and relies on dopamine to regulate muscle activity of smooth muscle.
Improving Sleep Health
- Consistent Schedule: Go to bed and wake up at the same time every day
- Sleep Environment: Create a dark, quiet, and cool bedroom
- Limit Screen Time: Avoid electronic devices before bedtime
- Healthy Lifestyle: Exercise regularly and maintain a balanced diet
