Why Sleep is Important

Published on Jan 01, 2024 | 12:03 PM

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Sleep is an essential need for the human body to function and plays a pivotal role in your heart's health, your immune system's strength, the effectiveness of your metabolism, and many other areas. It can often be the difference between a productive day and one where nothing gets done and is even celebrated annually in January with the Festival of Sleep and again in March on World Sleep Day. This leads to a commonly debated question: how much sleep do we need and why? (1)

How sleep works

There are several stages of sleep a person processes each night that consist of multiple cycles. These have been identified by monitoring Rapid Eye Movement (REM) and are broken down further into one REM and three non-REM stages. (2)

Sleep Cycle Stages

  • Stage 1: Also known as NREM Stage 1, is the initial phase lasting a few minutes, marking the transition from wakefulness to sleep. During this light sleep stage, muscle activity decreases, and individuals may experience hypnic jerks—sudden muscle contractions—along with fleeting dream-like images. (3)(4)
  • Stage 2: Known as NREM Stage 2, is characterized by deeper relaxation and accounts for a significant portion of total sleep time. Lasting around 20 minutes initially, it involves the appearance of sleep spindles and K-complexes—patterns of brain activity that contribute to the stability of sleep. During Stage 2, body temperature decreases, and heart rate slows down. (3)(4)
  • Stage 3: Also referred to as NREM Stage 3 or Slow-Wave Sleep, represents the beginning of deep sleep. Dominated by slow delta waves, this stage is essential for physical restoration, including muscle and tissue repair, energy replenishment, and the release of growth hormones. Stage 3 is characterized by a deep and restorative sleep, making it more challenging to wake someone during this phase. (3)(4)
  • REM Sleep: REM sleep, the final stage in the sleep cycle, is characterized by rapid eye movements, heightened brain activity, and vivid dreams. This stage is crucial for cognitive functions, emotional regulation, and memory consolidation. It is during REM sleep that most dreaming occurs, and the brain experiences increased blood flow. (3)(4)

Most common conditions that affect sleep

When it comes to conditions that affect a person’s capacity to sleep, the most common are sleeping disorders, with the most common among them being insomnia. Insomnia is a sleep disorder characterized by difficulty falling asleep, staying asleep, or experiencing non-restorative sleep, despite adequate opportunity for rest. It often leads to daytime fatigue, irritability, and impaired concentration. Further detailed in the Call-On-Doc Guide to Insomnia, the most common conditions that can accompany or cause insomnia include: 

  • Allergies: Allergies can disrupt sleep through symptoms like nasal congestion, sneezing, and itching, leading to difficulty breathing and discomfort. These issues, especially during allergy seasons, may contribute to insomnia or fragmented sleep. 
  • Restless Leg Syndrome: Restless Legs Syndrome induces uncomfortable sensations in the legs, compelling movement for relief. This sensory discomfort can hinder sleep onset and contribute to insomnia. 
  • Chronic Pain: Chronic pain conditions like arthritis and back pain or lasting effects from physical trauma frequently disrupt sleep.
  • Sleep Apnea: Sleep apnea manifests as interruptions in breathing during sleep, leading to fragmented and poor-quality sleep. Marked by loud snoring and daytime sleepiness, it should be attended to by a healthcare provider to improve a person’s health in the long term.
  • Gastroesophageal Reflux Disease: GERD causes acid reflux, particularly worsened when lying down, impacting sleep. 
  • Neurological Disorders: Neurological conditions like Parkinson's or multiple sclerosis may disrupt sleep due to discomfort and movement issues. 

Psychological conditions linked to difficulty sleeping

Other conditions that have been found linked to insomnia relate to a person's psychological wellness and mental health. The most common include: 

  • ADHD: Attention Deficit Hyperactivity Disorder) can make sleeping difficult due to heightened mental activity and challenges in regulating attention and impulses. Individuals with ADHD may experience racing thoughts, restlessness, and difficulty winding down, making it challenging to initiate and maintain sleep. The hyperactivity and impulsivity associated with ADHD can lead to irregular sleep patterns, impacting the overall quality and duration of sleep. (5)
  • Anxiety: Anxiety can disrupt sleep by causing persistent worry, restlessness, and heightened physiological arousal. Racing thoughts and anticipatory anxiety can make it challenging to relax and fall asleep. Individuals with anxiety may also experience physical symptoms such as muscle tension and increased heart rate, further hindering the ability to achieve restful sleep. The fear of the unknown or an overactive mind during nighttime hours often contributes to insomnia.
  • Depression: Depression can significantly impact sleep, leading to disruptions in both falling asleep and staying asleep. Individuals with depression may experience changes in their sleep-wake cycle, including insomnia or hypersomnia (excessive sleep). Persistent feelings of sadness, loss of interest, and a negative outlook can contribute to sleep disturbances. Sleep architecture may be altered, with an increase in rapid eye movement (REM) sleep during the early part of the night. 
  • Panic Disorder: A condition that can disrupt sleep through nighttime panic attacks, intense anxiety, and racing thoughts. Fear of having an attack during the night may create anticipatory anxiety, making it challenging for individuals to relax, initiate sleep, and maintain restful sleep patterns, contributing to insomnia and overall sleep disturbances.

How sleep affects the brain

Sleep plays a crucial role in supporting overall brain function and well-being. Here are several ways in which sleep affects the brain:

  • Memory Consolidation
  • Cognitive Function
  • Emotional Regulation
  • Brain Detoxification
  • Neurotransmitter Regulation
  • Hormonal Balance
  • Synaptic Plasticity
  • Conservation of Energy

How sleep affects your body

Adequate sleep is essential for maintaining overall physical health, and its impact extends across various bodily functions:

  • Immune System
  • Muscle Repair and Growth
  • Cardiovascular Health
  • Metabolism and Weight Management
  • Blood Sugar Regulation
  • Inflammation Regulation
  • Pain Perception
  • Hormonal Balance
  • Digestive Health
  • Cellular Repair and Maintenance

How sleep affects your mental health

Sleep is instrumental in promoting mental health by facilitating memory consolidation, emotional regulation, and cognitive functioning. Adequate and quality sleep helps the brain process and organize information acquired during the day, enhancing learning and problem-solving skills. It plays a crucial role in mood regulation, contributing to emotional resilience and reducing the risk of mood disorders such as anxiety and depression. Additionally, the restorative functions of sleep support overall cognitive well-being, helping individuals maintain focus, attention, and a positive mental state. 

If you’re suffering from insomnia, a chronic condition, or a psychological condition, Call-On-Doc can help you manage your overall wellness and get a good night's sleep again. Get the care you need today online with a same-day evaluation and prescription. Simply select the condition, answer a few medical questions to go over your medical history, and our providers take it from there. Your treatment plan will then be available in 2 hours or less!


  1. Suni, Eric, and Ealena Callender. “What Happens When You Sleep: The Science of Sleep.” Sleep Foundation, 22 12 2023, https://www.sleepfoundation.org/how-sleep-works/what-happens-when-you-sleep.
  2. Patel, Aakash K., et al. “Physiology, Sleep Stages - StatPearls.” NCBI, StatPearls Publishing, https://www.ncbi.nlm.nih.gov/books/NBK526132/.
  3. Suni, Eric, and Abhinav Singh. “Stages of Sleep: What Happens in a Sleep Cycle.” Sleep Foundation, 8 December 2023, https://www.sleepfoundation.org/stages-of-sleep.
  4. Patel, Aakash K., et al. “Physiology, Sleep Stages - StatPearls.” NCBI, StatPearls Publishing, 01 2023, https://www.ncbi.nlm.nih.gov/books/NBK526132/.
  5. Bhandari, Smitha. “Ways ADHD Can Cause Insomnia & Sleep Problems (And How To Fix It).” WebMD, 14 March 2023, https://www.webmd.com/add-adhd/guide/adult-adhd-and-sleep-problems.

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Wayne C. Hahne,

English graduate and Call-On-Doc’s medical resource guide, Wayne C. Hahne is an experienced and passionate medical education content expert. Through diligent research, provider interviews and utilizing the industry's leading resources for wellness information, it is Mr. Hahne’s personal mission to educate the general public on medical conditions with in-depth and easy-to-understand written guides.

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