Restorative Sleep
A large study of 500,000 UK adults revealed that 67% of us have disrupted sleep - and nearly 23% get five hours or less, each night. This same report identified the optimal amount of sleep as seven hours a night. Too little, or too much can have a direct effect on your cognitive performance and mental health.
Understanding the physiology of sleep can help us regain balance – and possibly bring a newfound respect for sleep as a fundamental process for good health, just like breathing or eating.
If you’d like to skip straight to practical tips on managing your sleep, scroll down to the section below. Alternatively, read on to better understand the physiological aspects of sleep.
Mechanisms of sleep
We have impressive biochemical processes that help us feel sleepy at night and keep us alert in the day. Our bodies are literally, synchronised with the earth. The light of day triggers certain hormones to get us going in the morning. The darkness of dusk indicates it’s time to wind-down and get ready for sleep. All of this is delicately orchestrated by hormones and neurotransmitters.
A reliable sleep-wake cycle provides restorative sleep needed for repair and optimal functioning the next day. Sleep is the ultimate recharge for our bodies.
There are two mechanisms at work in regulating sleep:
Homeostatic sleep drive. A sleep-inducing chemical called adenosine builds up in the brain during the day, eventually making you feel sleepy in the evening. The infamous caffeine is thought to block adenosine receptors disturbing sleep.
Circadian rhythm. This is our 24-hour internal master-clock, controlled by the brain. Our sleep-wake cycle is one example of many circadian rhythms.
As the sun rises, the retina in our eyes sense the increase in light, which starts a cascade of biochemical reactions leading to wakefulness.
The sleep-wake cycle is largely orchestrated by cortisol and melatonin.
In a typical cortisol curve, cortisol starts rising from 3am and peaks between 6am – 9am, acting as a “waking” hormone. The 3am activity of cortisol might explain random early-morning awakenings, which some people experience - particularly if they’re light sleepers or in a state of hyper-vigilance during stressful times.
As we begin to wake, this sleep-wake cycle also starts firing up various systems in our body such as thyroid or our digestive system. This is why it’s not unusual to have a bowel movement within 30 minutes of waking.
Later in the day, as darkness sets in melatonin levels start to rise inducing a sleep state.
Our ancestors lived in candlelight at night. In contrast, our modern world benefits from electricity, albeit digital screens and light pollution effectively and artificially extend day into night, possibly altering our natural biorhythms. If you’re continually exposed to light at night, it can shift your circadian clock back. Similarly, light exposure in the early morning shifts the clock forward (falling asleep earlier). The same effect can be seen in shift workers and their body adapts accordingly. Ultimately, the optimal sleep pattern varies from person to person. As long at your routine suits you and you’re getting enough hours of quality, deep sleep, then there is no one right way to do it.
The function of sleep
There are two functions at work, which are particularly important for health:
1 - Restoration, growth and repair.
After a day’s functioning, sleep gives the body a chance to clear metabolites produced by cells in our body, as well as toxins. Stronger urine that is concentrated with solutes in the morning is evidence of this. When you sleep your body temperature decreases, heart and breathing rate slows and muscles relax completely – it’s almost as though the body is shifting energy to support much-needed restorative functions overnight.
Cells divide into two to make new tissues – fundamental for healing after surgery or replacement of cells that are damaged including those cells which show signs of going ‘rogue,’ such as we associate with cancer.
A more recent discovery of the brain’s “glymphatic system” reveals that brain cells shrink by 60% at night. This allows more space for cerebrospinal fluid to occupy, which in turn enables it to clear away toxins and metabolites produced by cells in the day. A dysfunctional glymphatic system is, thought by some scientists, to play a role in Alzheimer’s disease (neurodegeneration).
During deep (slow-wave sleep) bone marrow activity increases producing more red and white blood cells. White blood cells are needed for immune system functioning. It’s no wonder we have the natural urge go to bed when we have the flu - and feel better after a good night’s sleep.
The early phase of sleep is pro-inflammatory, which may indicate suspicious cells or viruses and bacteria are dealt with overnight.
Growth hormone secretions are sleep-dependant and 75% of our growth hormones are released during sleep. Tissue regeneration and developmental changes are why babies need double the amount of sleep compared to adults. It potentially explains why teenagers need more sleep during puberty - the sex hormones required for these changes in adolescence are mostly sleep-dependent.
If you’ve done strenuous exercise in the day, more growth hormone is produced at night to regenerate the necessary tissues.
Major restorative functions in the body like muscle growth, tissue repair, protein synthesis occur mostly, or in some cases only, during sleep.
2 - Memory, cognition and brain plasticity.
The link between sleep quality and brain plasticity is becoming clearer in adults. Sleep maintains the pathways in your brain that help you to learn, remember, make judgements and perform a variety of tasks.
Poor sleep and general health
There are many studies about poor sleep. One study uncovered elevated blood pressure readings the day after a poor night’s sleep indicating an immediate impact on the body. In another study, subjects who slept four and a half hours per night reported feeling more stressed, sad, angry, and mentally exhausted.
In another, subjects who slept four hours per night showed declining levels of optimism and sociability. All of these self-reported symptoms improved dramatically when subjects returned to a normal sleep schedule.
Poor sleep and hunger hormones
Insufficient or low-quality sleep results in lower levels of leptin. Leptin is a hormone that alerts us when we’ve eaten enough food – the “satiety” hormone. Poor sleep also raises ghrelin – the hormone that stimulates appetite. This might explain why we crave pizza or chips when we’re tired. Our bodies’ hormones are driving us to choose high-calorific foods. We may also snack more when we’re tired.
Particular sleep scenarios
Chronic sleep disruption has been associated with (but not necessarily directly caused by) mood issues, fibromyalgia, cardiovascular disease, high blood pressure and weight gain.
Sleep and menopause:
Anxiety and insomnia are common symptoms reported by women who are establishing new hormone levels in this natural transition. Oestrogen plays a role in the metabolism of serotonin and other neurotransmitters involved in our sleep-wake cycle.
Herbalists help menopausal women develop a positive sleep routine and incorporate sleep-inducing herbal formulas to ease the transition. Nights sweats are also managed with anti-hidrotic herbs to minimise waking during the night.
The adrenal glands (which produce stress hormones) become strained in menopause due to the waning of the ovaries and reduced sleep quality or anxiety. For this reason, they need support. Adaptogenic and nervine plants buffer the body’s stress response and promote deep sleep. They also build emotional resilience in women who experience what is described as “meno-rage” which can be debilitating for women and confusing for family members.
Sleep, anxiety and depression:
Chronic and sustained stress puts a strain on your HPA-axis (hypothalamus-pituitary-adrenal) – the system that regulates stress hormones. These stress hormones bring about changes in the body to help you run faster, get more oxygen and think clearly to make life-and-death decisions. For example, when these stress hormones are released, blood circulation increases to your muscles, lungs and brain and reduces circulation to your core (gut and immune function is compromised). Cortisol makes you more alert. Glucose is liberated from your liver to give you more energy.
The brain and your adrenal glands work together to produce these stress hormones when a threat is perceived; real or not. Both the thought of a threat - or actually experiencing the threat will set off a cascade of stress hormones. Chronic and sustained engagement of this HPA system can affect your sleep as the same hormones (cortisol and similar) involved in the stress response are required to wake you up and keep you alert in the day. Depression is associated with a marked disruption in circadian rhythm.
Sleep and fibromyalgia:
Many people with fibromyalgia report disturbed sleep. Whether the sleep issues are causal or resultant is unclear but more research is showing that insomnia precedes pain symptoms in many fibromyalgia patients. Interestingly, increased pain sensitivity is a symptom of sleep deprivation which supports the idea of non-restorative sleep causing heightened pain sensitivity.
Some chronic fatigue syndrome (CFS) patients experience pain in their bodies where non-restorative sleep is a key issue in CFS. As well as sleep issues, hormone imbalance caused by stress is another factor meshed into sleep hormone dysregulation.
Sleep and neurodegeneration:
Sleep disturbance can be the first sign of neurodegeneration, for example, as seen in Parkinson’s disease. In Parkinson’s disease, the neurons producing dopamine are affected impacting the delicate interplay of neurotransmitters in which dopamine plays an important role.
TIPS FOR RESTORATIVE SLEEP
1. Enhance day and night
If you’re indoors mostly in the day, step outside at regular intervals (starting with waking) for natural light to stimulate your pineal gland signalling to your brain that its daytime. Conversely, darkness from dusk will trigger your sleep-inducing hormone system. It takes weeks (or some months) of consistency to establish a new biorhythm. If your biorhythm is out-of-whack, it’s not an overnight fix.
2. Set an alarm
To remind you to start your wind-down routine at the same time everyday if possible. Then, put away your phone and turn off the TV. Blue-light glasses or blue-light filters on devices may reduce blue-light stimulation in the eye as night approaches.
3. Bath before bed
This will raise your body temperature, but then subsequently lower it, which is conducive to falling asleep. Candles are preferable over electrical light. Try a few drops of lavender essential oil in the water. Lavender, clary sage or chamomile are neuro-relaxant herbs. Essential oils are inhaled via the steam entering the bloodstream reaching the brain.
4. Read a book or choose a sleep dream
A sleep dream is a positive memory you play over in your mind – it may be a childhood dream or recalling the details of a walk in a woodland. This is a kind of self-hypnosis, inviting the subconscious using imagination, not language. Do this lying down, eyes closed.
5. Yogic breathing or meditation
Meditation takes practise, but if done consistently the benefits will be gained. These activities engage the parasympathetic nervous system (passive state) and disengage the sympathetic nervous system (alert state).
6. Write it down
Write down a to-do list for the next day. This way, you go to bed feeling more confident and prepared for the next day and reduce the propensity for a 3am awaking or worrying overnight.
7. Hydrate sufficiently in the day
To avoid needing to go to the loo at night. Enough hydration in the day is needed to support your brain’s “glymphatic system,” which is switched on at night to clear away toxins.
8. Cool, dark room
This is beneficial for quality sleep.
9. Herbal medicine formulas
Herbal medicine from a herbalist are tailored to support each individual person depending on the need. Whether it’s calming anxiety during the day, inducing sleep onset, staying asleep, balancing blood sugars or reducing night sweats – practical lifestyle adjustments as well as herbal formulas are part of the plan. Restless leg syndrome is another common sleep disruptor that can be due iron-deficiency anaemia. Sleep-inducing plants works on GABA receptors as do the benzodiazepine class of drugs used for sleep and anxiety. You can find my article on valerian here.
10. Have your last meal earlier rather than later
Eating close to bedtime will fire up functional systems when your body should be winding-down.
11. Limit use of afternoon naps
A routine could develop with the possibility of changing your natural biorhythm.
12. Be active in the day
Enough physical exercise will help you fall asleep at night. Tire your body and your mind.
13. Stimulants
People metabolise stimulants at different rates. As a general rule, it’s best to avoid caffeinated drinks, sugar, alcohol, dark chocolate or stimulating herbal teas after 2pm.
If you easily feel the effects of caffeine, there’s a possibility you don’t metabolise caffeine well, or your liver may be overloaded in processing toxins. Caffeine competes with adenosine, which is a sleep-inducing chemical that builds up in the brain during the day eventually making you feel sleepy in the evening.
Alcohol is a central nervous system depressant initially, but when it is fully metabolised by the liver it becomes a stimulant. This potentially explains early morning awakenings after a night drinking alcohol.
14. Connected systems - look for the signs that your body is in rhythm
If you have a bowel movement shortly after waking (within 30-60mins) or feel most alert around mid-morning this could indicate your hormones are functioning optimally.
THE next steps…
If you struggle to get restorative sleep, it may be reassuring to know that herbal medicine could help. Partner a medical herbalist who can help unravel your experience to plan a positive way forward.
REFERENCES
Li, Y., Sahakian, B., Kang, J., Langley, C., Zhang, W., & Xie, C. et al. (2022). The brain structure and genetic mechanisms underlying the nonlinear association between sleep duration, cognition and mental health. Nature Aging, 2(5), 425-437. https://doi.org/10.1038/s43587-022-00210-2
insomnia, S. (2022). Sleepless cities revealed as one in three adults suffer from insomnia. Aviva.com. Retrieved 20 July 2022, from https://www.aviva.com/newsroom/news-releases/2017/10/Sleepless-cities-revealed-as-one-in-three-adults-suffer-from-insomnia/.
Brain Basics: Understanding Sleep | National Institute of Neurological Disorders and Stroke. Ninds.nih.gov. (2022). Retrieved 31 July 2022, from https://www.ninds.nih.gov/health-information/patient-caregiver-education/brain-basics-understanding-sleep#:~:text=Without%20sleep%20you%20can't,neurons)%20communicate%20with%20each%20other.
Function of sleep. Pmj.bmj.com. (2022). Retrieved 31 July 2022, from https://pmj.bmj.com/content/postgradmedj/52/603/15.full.pdf.
Why Do We Sleep, Anyway? | Healthy Sleep. Healthysleep.med.harvard.edu. (2022). Retrieved 31 July 2022, from https://healthysleep.med.harvard.edu/healthy/matters/benefits-of-sleep/why-do-we-sleep.
Besedovsky, L., Lange, T., & Born, J. (2011). Sleep and immune function. Pflügers Archiv - European Journal Of Physiology, 463(1), 121-137. https://doi.org/10.1007/s00424-011-1044-0
Siracusa, R., Paola, R., Cuzzocrea, S., & Impellizzeri, D. (2021). Fibromyalgia: Pathogenesis, Mechanisms, Diagnosis and Treatment Options Update. International Journal Of Molecular Sciences, 22(8), 3891. https://doi.org/10.3390/ijms22083891
Neurobiologic Mechanisms of Sleep and Wakefulness. FOCUS. (2022). Retrieved 31 July 2022, from https://focus.psychiatryonline.org/doi/10.1176/appi.focus.12.1.9.
Sleep Foundation | Better Sleep for a Better You. Sleepfoundation.org. (2022). Retrieved 2 August 2022, from https://www.sleepfoundation.org/.
Siracusa, R., Paola, R., Cuzzocrea, S., & Impellizzeri, D. (2021). Fibromyalgia: Pathogenesis, Mechanisms, Diagnosis and Treatment Options Update. International Journal Of Molecular Sciences, 22(8), 3891. https://doi.org/10.3390/ijms22083891
Xie, L., Kang, H., Xu, Q., Chen, M., Liao, Y., & Thiyagarajan, M. et al. (2013). Sleep Drives Metabolite Clearance from the Adult Brain. Science, 342(6156), 373-377. https://doi.org/10.1126/science.1241224
Besedovsky, L., Lange, T., & Born, J. (2011). Sleep and immune function. Pflügers Archiv - European Journal Of Physiology, 463(1), 121-137. https://doi.org/10.1007/s00424-011-1044-0
