Sleep - Explore the neuroscience of sleep and understand your brain's nightly journey
Science and Innovation
8/24/2024
6 minutes
THE NEUROSCIENCE OF SLEEP: UNDERSTANDING YOUR BRAIN'S NIGHTLY JOURNEY
Dr Jussi EerikäinenAs we sleep at night, our brains go on an interesting and unique journey.
That journey is an active process that impacts our cognitive health and overall sense of well-being. It demands the intricate orchestration of changes in brain activity levels, neurotransmitter concentrations, and hormones.
The sleep-wake cycle is a crucial process regulated by several brain regions, including the hypothalamus. Such a cycle is crucial for human physiology and health in everyday life by the input of light cues and the release of melatonin, respectively [1].
Each sleep stage is accompanied by increased activity in certain brain regions throughout the night. The thalamus, a sensory gatekeeper, takes a break from non-rapid eye movement sleep (non-REM). The rest of these sleep stages tend to straighten off, allowing us to block out the external world. The hippocampus, which is important for memory formation, becomes extremely dynamic during this phase, storing the day’s new memories in long-term storage [2].
Sleep is a stage-based process that follows distinct neural signatures throughout the course of the night. The two primary classes of sleep are non-rapid eye movement (non-REM) and rapid eye movement (REM). Non-rapid eye movement, or non-REM, is a phase when neuroactivity slows, and the body undertakes necessary maintenance processes to heal itself. When dreaming appears, rapid eye movement resembles wakefulness in the brain and develops eye movements while the body remains paralyzed. Many intense fantasies take place at this time, while memories are encoded through an emotional experience.
REM sleep is when our minds become active with imagined scenarios. This time, the visual and motor regions of your brain are firing full spread, while logic centers (prefrontal cortex) are experiencing layoffs. This is how our sensory superhighway takes control with an unbridled river rushed with imagination in place of rationality. This unique state of the brain may be able to account for why dreams are so often illogical [3].
A nightly dance with neurotransmitters, Adenosine accumulates while we are awake and helps induce sleep. Important brain function during rest and sleep, GABA (gamma-aminobutyric acid), gets activated as we slumber, inhibiting neural activity. On the other hand, acetylcholine increases activity during REM sleep, which is why our dreams are so vivid (4).
The importance of our nightly neural journey is enormous. Quality sleep is vital for cognitive functions such as learning and problem-solving. Research published in Nature Neuroscience shows that "repacking" information memories during sleep may help pre-existing densely stored information become easier to access and relate better to new facts [5].
Sleep also is a fundamental part of how you process your emotions. After a night of ‘no sleep,’ the amygdala (the part of your brain responsible for emotional processing) reacts to things more sensitively... which may explain why we become more irritable when tired. Current Biology presents data suggesting that sleep assists in emotional processing and regulation [6]
Knowing the complexities of sleep gives us a chance to properly value it as one of our most important human needs. By following our natural circadian rhythms (the 24-hour cycles by which all of our cells operate) and ensuring we get quality sleep, we enable our brain to perform crucial nocturnal activities rather than just passively rest.
Embark on your own journey to sleep optimization today. Start recording your bedtime and wake time, as well as the quality of your sleep, in a weekly sleep diary. When you prioritize sleep, you are also investing in your cognitive health and general well-being.
Sweet dreams—and happy brain-boosting!
References:
- Saper, C. B., Scammell, T. E., & Lu, J. (2005). Hypothalamic regulation of sleep and circadian rhythms. Nature, 437(7063), 1257-1263.
- Diekelmann, S., & Born, J. (2010). The memory function of sleep. Nature Reviews Neuroscience, 11(2), 114-126.
- Hobson, J. A., & Pace-Schott, E. F. (2002). The cognitive neuroscience of sleep: neuronal systems, consciousness, and learning. Nature Reviews Neuroscience, 3(9), 679-693.
- Saper, C. B., Fuller, P. M., Pedersen, N. P., Lu, J., & Scammell, T. E. (2010). Sleep state switching. Neuron, 68(6), 1023-1042.