Sleep Science
Find out more about the different stage of sleeps and their benefits and the difference between REM and Non REM sleep.
Chronotype
Are you an early bird or a night owl? Chronotype is the natural inclination of someone’s body to sleep at a certain time during a 24-hour period.
Circadian Rhythms / Sleep-Wake Cycle
The circadian rhythm is a natural 24-hour cycles that are part of the body’s internal clock, running in the background to carry out essential functions and processes.
Sleep Architecture
A typical night’s sleep consists of multiple sleep cycles, each lasting about 90-120 minutes. These cycles progress through the different sleep stages, starting with NREM sleep and transitioning into REM sleep. As the night progresses, the duration of REM sleep increases, while the duration of deep N3 sleep decreases.
Sleep Regulation
The sleep-wake cycle and sleep stages are regulated by a combination of neurotransmitters and hormones. Adenosine, a neurotransmitter, gradually builds up in the brain while we are awake, promoting sleep pressure. When we sleep, adenosine levels decrease, reducing sleep pressure. Other neurotransmitters like serotonin, norepinephrine, and acetylcholine also play roles in sleep regulation.
What Are the Stages of Sleep?
Stage 1 – Hypnogogic
Hypno (sleep), Ggōgos (leading) – Non REM
- Stage 1 is your doorway into sleep
- Neurologically, this stage of sleep is accompanied by alpha and theta brainwaves, which are associated with states of hypnosis and deep relaxation.
- We might experience sudden bodily spasms, known as ‘myoclonic jerks’
- Your eyes are closed, and you feel very drowsy and have micro dreams It would be mainly images from your days, they can be clear or psychedelic
- We can hear the sounds in the room and still feel our body in the bed.
Stage 2 – Light Sleep – Non REM
- Neurologically, light sleep is dominated by theta brainwaves.
- We spend more time in light sleep than in any other stage, light sleep makes up about 50 per cent of our total sleep time
- We experience the dissolution of external awareness, and we black out.
- Our heart rate starts to drop, our body temperature lowers, our eye movements stop and our brainwave activity slows down
- Light sleep plays a critical role in memory consolidation.
- It helps to consolidate declarative memories, such as
- factual information
- New words or instructions
- It helps to consolidate declarative memories, such as
Stage 3 – Deep Sleep – Non REM
- Your brain is in delta-wave; very low-frequency delta waves and we enter the deepest level of sleep.
- Our brain is highly deactivated, and if we are woken from it, we’ll commonly feel groggy and disorientated.
- Without deep sleep, our brain function is greatly impeded the next day. Deep delta-wave sleep is also essential for general bodily repair, as it’s the state in which HGH, human growth hormone, is released. This makes our cells regenerate and our hair, nails and muscles grow
- Most of our deep sleep in the first four hours of our sleep cycle. This is why we can physically survive for quite a while on just four hours of sleep.
REM Sleep
- REM Sleep was originally called paradoxical sleep because it involves seemingly contradictory states of an active mind and a sleeping body; your body is off while your brain is switched on.
- During REM Sleep our body consolidates more complex information and emotional memories. The sleep expert Professor Matthew Walker , “Why we sleep” famously stated: “We dream to remember, and we dream to forget.”
- Dreaming is an active sleep state – our brainwave activity, breathing and blood pressure all increase to near waking levels, while the actual process of dreaming requires so much neurological energy that it even burns calories.
- During REM sleep in both the hippocampus and the cortex, theta wave activity predominates; electrical connectivity among different parts of the brain manifests differently than during wakefulness research.
- And then we have REM stage, which is very interesting because in REM sleep it’s very much like being awake. So we’re back to beta waves as we saw when you are awake and alert. The brain part of the brain which is associated to emotion area of the brain becomes more active (30%), the right brain gets more blood flow. AND during the lucid state, the parts of the brain which are switched off during the REM stage – the frontal lobe and all parts related to meta cognition and meta reflexion are now switched on. So, we have both parts of the brain super active.
- Our body doesn’t move, though – it becomes paralysed, so that we don’t act out our dreams. A part of the brain called the pons sends a signal to the spinal cord to paralyse the major muscle groups.
- Dreaming is just as essential to our health as neurotoxin-removing deep sleep.
- In fact, when we’re sleep-deprived, our brain actually prioritizes dreaming over the other three stages of sleep.
Sleep Cycle Architecture
EED Recording stage sleep & brain waves
What Hormones Impact Sleep?
Melatonin is often referred to as the “sleep hormone” because it plays a central role in regulating the sleep-wake cycle. It is produced by the pineal gland in the brain, primarily in response to darkness. Melatonin levels rise in the evening, signaling the body to prepare for sleep. It helps promote drowsiness, decrease alertness, and regulate the timing of sleep
Adenosine
Adenosine is a neurotransmitter that gradually builds up in the brain while we are awake. The accumulation of adenosine creates sleep pressure, contributing to the feeling of tiredness. When we sleep, adenosine levels decrease, reducing sleep pressure and promoting wakefulness upon waking.
Growth Hormone
Growth hormone is primarily secreted during deep sleep, specifically during the slow-wave sleep stage (N3). It plays a vital role in tissue repair, cell regeneration, and growth. Adequate deep sleep is necessary for the proper secretion and function of growth hormone.
Serotonin
Serotonin is a neurotransmitter that is involved in various functions, including mood regulation and sleep-wake cycles. It is synthesized from the amino acid tryptophan and converted into melatonin. Adequate serotonin levels are necessary for the synthesis of melatonin, which helps regulate sleep.
Orexin/Hypocretin
Orexin, also known as hypocretin, is a neuropeptide that promotes wakefulness and regulates arousal. It helps stabilize wakefulness and sleep transitions. A deficiency of orexin can lead to narcolepsy, a sleep disorder characterized by excessive daytime sleepiness.
Prolactin
Prolactin is a hormone primarily associated with lactation in females. It is also involved in regulating sleep and has been linked to sleep homeostasis, the process that regulates the balance between sleep and wakefulness.
What Are the Factors that Affect Your Sleep?
- External factors: Light exposure, noise, temperature, and comfort of the sleep environment.
- Internal factors: Stress, anxiety, physical activity, and certain medical conditions.
- Lifestyle factors: Diet, caffeine and alcohol consumption, and medication use.
- Individual differences: Age, genetics, and personal sleep preferences
