Basic Neuroscience Series – Sleep

Articles Basic Neuroscience Series

Sleep is essential. I mean, you spend about one-third of your life asleep, you don’t feel well when you’re sleep deprived and when your sleep quality is bad. But what exactly is sleep and why do we need it?

Why is sleep important?

Here are a few examples as to why sleep is important:

  • Sleep improves your immune function
  • Good sleepers regulate calories better
  • Good sleep can improve concentration, productivity and memory
  • Good sleep can maximize athletic performance
  • Poor sleepers have a greater risk of heart disease, stroke and diabetes
  • Poor sleep is linked with depression
  • Poor sleep is linked with increased inflammation
  • Sleep deficits can increase your risk of Alzheimer’s
  • Sleep loss may reduce your ability to interact socially

Learn more here: “What happens to your body and brain if you don’t get sleep – Matthew Walker” ; “What would happen if you didn’t sleep? – Claudia Aguirre”.

Sleep stages

There are two types of sleep: rapid eye movement (REM) sleep and non-rapid eye movement (non-REM) which is made up of 3 stages.

Stage 1: The first stage of non-REM sleep involves the transition from wakefulness to sleep.  This stage of sleep is light as brain waves begin to slow from wakefulness patterns. Your heartbeat, eye movements and breathing slow down.

Stage 2: The second stage of non-REM sleep takes place prior to entering deeper sleep. Your muscles relax, body temperature drops, and eye movements stop. Your brain-wave activity gets ever slower but has brief bursts of electrical activity. This is the longest stage of the sleep cycle.

Stage 3: The third and final stage of non-REM sleep involves deep sleep which occurs in longer periods during the first half of the night. Your muscles are fully relaxed and brain waves are slow. Your heartbeat and breathing are at their slowest.

REM sleep: REM sleep involves the rapid movement of eyes from side to side, which occurs approximately 90 minutes after sleep begins. This is also the stage when most dreaming occurs. Your brain wave activity becomes closer to what is seen in wakefulness. Your heart rate and blood pressure increase to near-waking levels and your breathing rate increases and is irregular. Your arm and leg muscles become fully paralysed.

Learn more here: “A walk through the stages of sleep – Matthew Walker”

Source: Backyard Brains, Experiment: Sleep 2017.

The brain and sleep

Multiple brain structures take part in sleep, for example:

The hypothalamus and suprachiasmatic nucleus (SCN): The hypothalamus controls centres that affect both sleep and arousal. Within the hypothalamus, the SCN is involved in tracking your behavioural rhythm, by sensing light exposure for example. This allows your body to establish a biological clock, which helps to control when you feel awake or sleepy (circadian rhythm).

The brainstem: The brainstem sends signals to the body allowing muscles to relax during sleep. The brainstem also communicates with the hypothalamus to control sleep and arousal: together they produce a chemical (called GABA) which reduces activity within arousal centres.  

The pineal gland: The pineal gland receives signals from the SCN to increase the production of a hormone called melatonin, allowing you to sleep.

The amygdala and the thalamus: Both of these structures become quiet during most sleep stages. However, they are generally active during REM sleep dreaming. The amygdala is involved in processing emotions during dreams and the thalamus relays sensory information (such as sounds, smells, images, etc.) to the cerebral cortex.

Source: Unihemispheric slow-wave sleep, Biology 342 (2006).

Tips for good quality sleep

  • Relax before bed: avoid bright lights and loud sounds, don’t use your phone/laptop/TV, try reading or taking a warm bath
  • Go to sleep and wake up at the same time each day
  • Do not exercise in the few hours before bed
  • Avoid caffeine, alcohol and nicotine before bed
  • Do not work in your bed (only associate your bed with sleep)
  • Keep your room at a comfortable temperature
  • Don’t lie in bed awake, wait until you are sleepy to get in bed
  • Get around 8 hours of sleep per night
  • Go to a sleep clinic to get sleep support!

Learn more here: “6 tips for better sleep – Matthew Walker”

Featured image source: “Pocket: How many hours of sleep do you actually need? Maldarelli.”

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