Brain Health: Sleep
Sleep Quality and Sleep Quantity
The next topic in the brain health series is the quality and quantity of sleep.
We all have those moments when we just want to stay in bed without having to wake up before daybreak to get ready for work or school. Sometimes we find ourselves in bed staring at the clock at 2am not being able to fall asleep and spending the rest of the day feeling like a zombie. While on separate occasions we end up sleeping for a solid 10 hours, only to wake up feeling dreadful nonetheless.
How much sleep should we really be getting every night to function optimally throughout the day?
How do we ensure that we are getting quality sleep that leaves us feeling energized and ready for the day ahead?
First, let's break down the phases of sleep. There are two phases of sleep, rapid eye movement sleep (REM) and non-rapid eye movement sleep (NREM). NREM sleep is further divided into three stages, N1, N2 and N3 sleep. Our sleep occurs in four to five cycles that typically last 90 minutes to 2 hours each. The sleep cycle begins with N1 sleep, followed by N2 and N3 sleep, which then leads to REM sleep.
N1 sleep is the stage of sleep when one is feeling drowsy and is falling asleep. This stage of sleep is characterized by theta waves on EEG recording and is a duration of approximately 5 minutes.
N2 sleep is a light stage of sleep. During this stage synaptic plasticity and memory consolidation occurs. This stage of sleep is characterized by sleep spindles and theta wavebands on EEG recordings and is usually 20 minutes in duration. However, the duration of N2 sleep increases with each sleep cycle.
N3 sleep is deep sleep. This stage of sleep is vital for the repair and regeneration of various tissues, cells, bones and muscles in the body. This sleep is characterized by delta waves on EEG recordings and comprises roughly 25% of our total sleep.
REM sleep is the stage of sleep when we dream. Our brain is highly active during this stage, and our brain waves a similar to that of wakefulness. Interestingly, our brain's metabolism increases by 20% during this phase of sleep. Memory consolidation, processing of emotions, and various neurological alterations necessary for brain development occur during this phase of sleep.
Without adequate sleep one may experience difficulty in focusing, recalling information and staying alert during the day. Long-term sleep deprivation or chronic loss of sleep has been associated with poor mental health and metabolic illnesses such as diabetes. Therefore, it is evident that sleep is important for maintaining overall health, including brain health. So how much sleep should we be getting every night?
Here is the recommended amount of sleep for each age group:
- Ages 1-2 years: 11-14 hours of sleep
- Ages 3-5 years: 10-13 hours of sleep
- Ages 6-12 years: 9-12 hours of sleep
- Ages 13-18 years: 8-10 hours of sleep
- Adults 7-9 years: 7-9 hours of sleep
- Maintain a healthy circadian rhythm by exposing your body to natural light (safely) during the day
- Exercise
- Don't take naps longer than 30 minutes
- Avoid substances such as caffeine, alcohol and nicotine before you sleep
- Limit your exposure to blue light ( emitted from phone screens, TV screens and laptop screens) at least an hour before sleep. Blue light emissions may interfere with hormones such as melatonin which are important for inducing sleep.
- Synaptic plasticity is the process of altering the connections between neurons depending on how often the neural connections are used. The more one uses particular neural connections, the greater the connectivity and communication between those neurons are.
- Memory consolidation is the process whereby memories are stabilized so that the memory lasts longer.
- Circadian rhythm: your "internal clock" that regulates alertness and sleepiness according to changes in light in our environment. This biological clock is controlled by the suprachiasmatic nucleus (SCN) in the brain.
- Melatonin: a hormone that is released by signals from the SCN in response to darkness and is responsible for inducing sleepiness. This hormone is not released when blue light is detected. Melatonin plays various roles such as an antioxidant, and metabolic regulator and protects the heart and nervous system.
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