The importance of a good night’s sleep

No matter how much we take care of our bodies while we are awake, sleeping poorly can erase many of those gains. In order to be successful, happy and healthy, we must pay attention to the quality of the sleep we are getting.

November 15, 2020 | Ashley Moriarty, DPT, OCS


No matter how much we take care of our bodies while we are awake, sleeping poorly can erase many of those gains. We must pay attention to the quality of the sleep we get to be successful, happy and healthy.

Defining Sleep

Sleep is a naturally occurring, easily reversible state that is marked by the absence of wakefulness and a loss of consciousness. It is typically associated with certain body postures (such as lying down with your eyes closed) and marked by changes in brain activity. It is considered essential for the recovery of the body’s physical and mental functions.

In terms of evolution, sleep would be considered a weakness. If the goal is survival, sleeping, with its accompanied loss of consciousness and incognizance of surroundings, would leave you vulnerable to predators. So why then, do we spend so much time sleeping? In order to determine its importance, most researchers assess what happens when someone is deprived of sleep. Studies have shown that as little as 24 hours of sleep deprivation can lead to hallucinations and psychosis. Lack of sleep is also is correlated with higher incidences of heart disease, diabetes, cancer and other illnesses. Sleep is good for overall health both physically and mentally, but it is primarily a restorative process for the brain.

On average, your brain uses only half the usual amount of glucose (energy) during sleep, allowing your energy reserves to be restored. It drives out toxins, clearing out waste products that are created during the day. Most importantly, however, sleep helps with neuroplasticity, or your brain’s ability to learn new skills, create new memories and evolve.

Sleep Requirements

Adults require eight hours of sleep. One could function on less, but that would create a sleep deficit, causing physical and mental harm. Overall, Americans get 6.8 hours of sleep per night on average, a number trending down each year. Work schedules are busier, modern society encourages us to stay up later and wake up earlier and there is more pressure for daily productivity.

School-age children and teens require 10–12 hours of sleep. As a result, some school districts opt for later start times to allow kids to get a full night’s sleep. Preschool-age kids need 10–13 hours, and toddlers need even more than that, somewhere around 11–14 hours.

Breaking Down Sleep Cycles

Sleep can be broken down into REM and non-REM states, with non-REM being further broken down into three phases.

  • Non-REM phase one begins when you start moving from being awake to asleep. The pattern of your brainwaves change, your muscles begin to relax — although you may experience muscle twitching — and heart rate and breathing begin to slow.
  • Non-REM phase two follows as a period of light sleep, like phase one. Brain wave activity slows with occasional bursts, body temperature drops and heart rate and breathing continue to slow.
  • Phase three, often considered the most important phase, is deep sleep. Heart rate and breathing are at their slowest and your brain is restoring energy. It is during this phase that memories are created and hormones are release to aide in tissue healing and growth. This phase tends to be longer during the earlier hours of sleep, but shorter as you get closer to waking up.
  • REM stands for rapid eye movement and is a phase marked by side to side eye movements, higher brainwave activity and dreaming. Your arms and legs are slightly paralyzed during this phase as a protective mechanism to prevent flailing as you dream. You reach your first REM phase about 90 minutes into sleep and cycle through all stages throughout the night.

A person can go through all sleep cycles three to four times a night, although this fluctuates from people to person. Improving sleep hygiene can lead to a more predictable and consistent sleep pattern. Ideally, adults should spend 20–25% of total sleep time in REM sleep and phase 3 non-REM should be around 13–23%. On the other hand, toddlers should spend half of total sleep in REM sleep and the other half in phase three non-REM sleep. Because both cognitive and motor memories are created in deep sleep, toddlers need a high amount of it. Since they are leaning and developing at such a rapid rate, it only makes sense that toddlers benefit from the sleep phase that aides in neuroplasticity.

Impact of Sleep on the Body's Recovery

Sleep can also affect immune function: generally speaking, good sleep acts positively on the immune system, and bad sleep acts negatively. Cortisol, the stress hormone, decreases at night, while human growth hormone and prolactin, both released naturally, increase at night to promote tissue healing. T cells, the body’s fighter cells, and their helper cells both function better with higher quality sleep. Poor quality sleep can lead to impaired cognitive function and impaired memory, and can have long term consequences. This includes an increased risk of cardiovascular disease, hypertension, coronary artery disease and diabetes. A good night’s sleep is necessary to allow your body to recover properly.

How to Get a Good Night's Sleep

You can take a guess at how good your sleep is based on how rested you feel in the morning or how soundly you slept through the night. However, the best way to really find out if you are getting high quality sleep is to track it. One sleep tracking device that we use at Performance is the Oura ring. You wear the Oura ring for three to four weeks to establish a baseline for yourself. It tracks how well you sleep, how frequently are you sleeping well and how much sleep are you getting. Once that is complete, you can reassess your approach to sleep.

If you are not getting good quality sleep or enough of it, there are many strategies to help, outlined below. We suggest implementing one or two at a time and seeing what works best for you.

Tips For Improving Sleep Quality:

  • Avoid caffeine late in the day. Caffeine has a half-life of six hours, so if you have a cup of coffee at 12 p.m., at 6 p.m. there is still half of it left in your system, and it is not fully out of your system until midnight.
  • Avoid alcohol, as just one drink can create sleep problems. Yes, alcohol is a sedative and may help you fall asleep, but it will not be a natural sleep, but fragmented with periods of wakefulness throughout the night. Drinking decreases REM sleep and learning capacity and can even affect memory formation days later.
  • Decrease artificial light throughout the day. Our bodies release melatonin in response to darkness, so getting more light later in the day decreases our levels of circulating melatonin.
  • Use blue light glasses for LED bulbs, such as those found in screens such as phones, tablets and TVs. Blue light is a daytime stimulus, so try minimizing exposure two to three hours before going to bed.
  • Keep your bedroom dark. Avoid putting a TV in your room and use blackout curtains or a sleep mask.
  • Keep your bedroom cool. 65 degrees Fahrenheit or lower has proven to be ideal for sleep.
  • Help lower your body temperature: wash your hands or face before bed to stimulate body temperature change. Do not wear socks and try keeping your hands and feet out of the sheets.
  • Make time to wind down. Dial into your parasympathetic nervous system, practice mediation, mindfulness or deep breathing.
  • Maintain a regular sleep schedule, even on weekends.