Sleep is one of the most important aspects of good brain health. In fact, it is the first thing I try to help my patients get sorted. Without sleep, our brain's just do not and cannot optimally function. So why would we expect our brain's to rehabilitate well if we are not getting adequate, quality sleep?
Stages of Sleep
Non-REM 1 is the stage where your mind and body relax and slow down, marked by a decrease in heart and respiratory rate.
Non-REM 2 is when your body temperature drops and your heart rate and breathing become more regular. You spend about 50% of your sleep in this phase.
Non-REM 3 is known as "deep sleep" because most external stimuli will not wake you up. This stage of sleep is restorative with increased immune activity, insightfulness, and memory consolidation. If you have ever woken up from a night of sleep, but do not feel rested, then you most likely did not get enough deep sleep. Similarly, if you wake up in the middle of deep sleep, you will feel groggy. Ever woken up from a deep nap? You know what I mean.
REM begins approximately 90 minutes after you have fallen asleep. It is very similar to wakefulness in terms of brain activity. During this stage, emotions are processed and stored, learning happens, and you dream vividly.
Circadian Rhythm
Circadian rhythm is our internal biological clock that regulates our sleep-wake cycle. It is orchestrated by our brain's ability to release hormones either directly from the pineal gland (melatonin) or indirectly through the hypothalamic-pituitary-adrenal axis (cortisol). Cortisol stimulates our brain and is at its highest in the morning to signal our body to wake up. Melatonin produces a chemical reaction in our brains that causes drowsiness and is at its highest level in the evening to signal our body to go to sleep. Cortisol and melatonin have an inverse relationship with one another: when one rise, the other falls.
Secretion of these hormones is partially controlled by light. With morning (and artificial) light, melatonin secretion is diminished and cortisol secretion is elevated. Our ancestors living in times before artificial light naturally rose with the sun and slept when dark. The introduction of artificial light, especially blue light as found in electronics, affects the secretion of melatonin and cortisol, and thus our circadian rhythm is altered. This is why it is discouraged to look at your computer, phone, tablet, or TV within an hour or two of going to bed. When doing so, you are unnaturally diminishing the secretion of melatonin, and thus diminishing the signal for your brain to go to sleep.
Stress and sleep
Stress can also impact our circadian rhythm. When we are emotionally or psychologically stressed, our body releases cortisol to increase alertness and activate our fight-flight response. This is normal and is meant to protect us in times of threat. Once the stressor is removed, cortisol levels return to their baseline. This is also normal. However, in cases of chronic stress, cortisol levels can remain high and never return to their baseline. This long-term elevation of cortisol has an impact on many aspects or our health, especially sleep.
Feeling constantly stressed elevates cortisol levels, keeping us over-stimulated (or in fight or flight mode). Elevated cortisol levels flatten the circadian curve shown above causing the secretion of melatonin to decrease. Decreased melatonin secretion makes it difficult to turn off our brains and fall asleep. This sleep deficit then creates more stress, more cortisol, and the cycle is perpetuated. This is why stress management plays a significant role in getting your sleep back on track.
Concussion and sleep
After a concussion (mild traumatic brain injury) you can have difficulty falling and/or staying asleep (insomnia) or sleeping too much (hypersomnia). It is common to have hypersomnia immediately after a concussion, for up to one week. In adolescents with a sport-related concussion, sleep disturbances beyond this acute phase have been found to correlate with more post-concussive symptoms and a longer recovery time (1). While the underlying cause of these sleep deficits are not clearly understood, there is evidence of neurotransmitter (glutamate) and neuropeptide (orexin/hypocretin) imbalances, as well as decreased melatonin production, as being contributing factors of sleep dysregulation after traumatic brain injury (2). Treatment for sleep disturbances ranges from conservative to pharmacological/medical management. Conservative treatments include sleep hygiene, Cognitive Behavioral Therapy (CBT), craniosacral therapy, acupuncture, and blue light therapy (3). As a physical therapist, I encourage my patients to start conservatively with sleep hygiene strategies (see below) and explore other options if these strategies aren't effective.
Side note: After a concussion, some people experience light sensitivity (photophobia), especially that of a computer or tablet, and may wear blue light filtering glasses when working on these devices. In considering blue light therapy and the role blue light plays in signaling production of cortisol and initiating wakefulness, I encourage my patients with concussion to reduce the use of blue light filtering glasses during that day. Blue light is necessary in maintaining a normal circadian rhythm.
Key elements to good sleep hygiene
BE CONSISTENT - Go to bed and wake up the same time each day, even on weekends. Think of your brain like a newborn or a puppy. Consistency is key when sleep training a child or dog. The same goes for the brain.
DEVELOP GOOD SLEEP HABITS - Up to one hour before your bedtime, take a warm bath, drink non-caffeinated hot tea, listen to music, or read with soft lighting. Doing this consistently signals to the brain that it is time to go to sleep (remember the puppy analogy?). AVOID watching TV, looking at your phone or tablet, or consuming caffeine, alcohol, or nicotine. These are all brain stimulating activities or substances.
SLEEP WHEN SLEEPY - Try not to lay awake in bed for more than 15 minutes and avoid watching the clock. Get up and do something (not a brain stimulating something) and then try again. Avoid napping during the day, but if you have to, limit naps to 20-30 minutes by setting an alarm.
CREATE A GOOD SLEEP ENVIRONMENT INSIDE AND OUT - Maintain a quiet, cool, dark, and comfortable room. Quiet any noise in your head by writing down your perpetual "to-do" list, worries, or ideas on a piece of paper right before you go to bed. They will be there for you to think about in the morning.
There are many reasons for experiencing difficulties with sleep, including: stress and anxiety, respiratory conditions, chronic pain, and concussion or brain injury, to name a few. There are also many types of sleep disorders, including: insomnia, hypersomnia, narcolepsy, sleep apnea, etc. Therefore, treatment should be targeted to your specific cause and condition. if you are experiencing difficulties with sleep, it is important to let a healthcare provider know, so they can direct you to the right resources.
Goodnight room, goodnight moon, goodnight brain.
Sleep Resources
Sleep Apps
Calm - Calm provides guided meditations of various lengths which incorporate soothing music, nature scenes/sounds, and breathing exercises to help reduce anxiety and ensure a restful night of sleep.
Rainy Mood - provides soothing audio of rainfall to assist with sleeping, working, and relaxing.
References
Kostyun RO, Milewski MD, Hafeez I. Sleep disturbance and neurocog- nitive function during the recovery from a sport-related concussion in adolescents. Am J Sports Med. 2015; 43(3): 633–640.
Sandsmark DK, Elliott JE, Lim MM. Sleep-Wake Disturbances After Traumatic Brain Injury: Synthesis of Human and Animal Studies. Sleep. 2017;40(5):zsx044.
Aoun R, Rawal H, Attarian H, Sahni A. Impact of traumatic brain injury on sleep: an overview. Nat Sci Sleep. 2019;11:131-140.
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