Why sleep matters and how to get better sleep?
Have you ever experience an episode in life that you caught a mild infection or common cold after staying up late for several nights or missed a few nights of quality sleep? Part of the reason is that there are many important biochemical processes that happen during sleep and these processes help to ‘prime’ the immune system into healthy action. When a person is sleep deprived, these immune responses can be hindered and may even increase the likelihood of the person catching a cold. Despite its importance, sleep is often neglected and overlooked as a powerful modifiable lifestyle strategy to improve immune health. This is because sleep and our circadian system are strong regulators of immunological processes. 
The basis of this influence is a bidirectional communication between the central nervous system and immune system which is mediated by shared signals (neurotransmitters, hormones and cytokines) and direct nerve supply to the immune system by the autonomic nervous system.
There is substantial evidence to suggest that even one night of reduced sleep can cause disturbances to our innate immune system. [3,4] These disruptions are mainly due to the inflammatory signals produced during the two interactive processes that regulate our sleep: sleep/wake homeostasis and the circadian clock. The homeostatic process is one that drives us to sleep by telling us about the need for sleep and it is time to sleep. The circadian process is an the internal oscillatory rhythm that regulate the timing of periods of sleepiness and wakefulness throughout the day, and can be reset by the environmental light .[5,6] In chronic sleep conditions like insomnia or long-term reduced quality of sleep, activities of immune cells are likely to get affected.
Preventive and Restorative
As mentioned above, lack of sleep could be linked to the early stage of an infection, it can also slow down the immune system and allow the illness to progress further. Interestingly, illness can further disrupt a person’s sleep and slowing down the recovery.[8,9] That’s probably why we are advised to get “lots of rest” when we fall sick, and that could be the best approach to bolster your immune responses. So, bottom line is that the benefits of sleep are both preventive and restorative. Due to its restorative and regulatory abilities, getting good quality and adequate quantity (seven to eight hours) of sleep is of utmost importance as part of immune maintenance, as well as during the recovery period from illness.
Sleep influence on stress responses, social relationship/connection and other bodily functions
In my previous article, I discussed the importance of managing stress and one of the suggested strategies to manage stress is to get proper sleep. That’s because sleep and stress interact closely in a bidirectional fashion.  It is evident in one study that the duration of stress can affect our perception of stress, which is critically important at this challenging time, demonstrating the influence of sleep has on our state of mental resilience. So, restore your sleep to make sure that you don’t get affected emotionally and psychologically. 
Another important reason that sleep is so essential is because it alters the physiology across many body systems.  Both short- and long-term health consequences in individuals across all ages have been well-documented, including by not limited to increased stress responsiveness, pain, emotional distress, memory, performance deficits, hypertension, dyslipidemia, cardiovascular disease, weight-related issues, metabolic syndrome, type 2 diabetes mellitus, and brain-related disorders. [13,14,15,16,17,18]
Its regulatory role in many physiologic functions has therefore associate it to many conditions/disorders like mental performances, risk of neuro-degenerative disorders, cardiovascular disease,and/or diabetes, all of which are rising in numbers in recent years and decades. Therefore, even if it is not for the benefit of your immune system, prioritizing sleep into your overwhelming day to day “to-do list” will never a bad idea for your general well being.
Put aside all the above-mentioned medical conditions, even social relationship and connection can be influenced by sleep. Considerable amount of evidence suggests the lack of these essential relationships can upregulate pro-inflammatory processes[20,21] and reduced immune functionality (e.g., NK cell activity).Moreover, it has been shown that improved sleep efficiency can lower an inflammatory molecule (IL-6), which was enhanced in those with positive social relationships. This is significant as social relationships are a notable determinant of immune health and the lack of quality sleep can have profound effects on the way we perceive our world, navigate our day.
Simple strategies to get better quality of sleep
- Avoid staying up late and practice consistency in sleep schedule – One of the most common reasons that people do not get adequate amount of sleep is that they didn’t go to bed when it’s time to sleep, and forced to wake up to start their daily routine in the morning. Try to organize your tasks around and make sure you go to bed when your body tells you to is the first action step you need to implement. Having to go to bed and wake up around the same time every day reinforces the two processes that we talked about and it will help to maintain a better consistency in your sleep schedule.[23,24,25]
- Daylight vs Artificial light – It is proposed that daylight helps to make it easier for a person to fall asleep at night by reinforcing the “awake” phase of the sleep cycle. During this period of time, if you are staying indoor most of the day, try sit close to a window and take breaks to look outside. In the evening and night, try to avoid long hours of usage with electronics as blue lights from these devices can stimulate alertness.[26,27,28]
- Avoid Stimulants and Salty Food (especially at night) – Stimulants like tea, coffee, caffeinated drinks may keep you alert throughout the night and prevent you from falling asleep. Apart from keeping you alert, caffeine can get you up in the middle of the night (as many of these drinks are diuretics) to run to the toilet. Either way, your sleep may be disturbed. Similarly, salt is also a diuretics. The more you take, the more urine need to get expelled to get rid of it from your system. Because salt also make a person feel thirsty, the increase in water intake again increases the need to urinate, particularly at night. [29,30,31]
- Nighttime tension, take time to unwind – This is very unique to everyone. Nighttime tension may range from an argument, anxiety-provoking news or activities, reading and analyzing the stock market to trivial routine like paying bills. If you are able to notice activities that may cause tension and prevent you from falling to sleep, it is best to avoid them before your bedtime. If you are anxious or your mind is constantly active, take additional time off to calm yourself down may be helpful to prepare yourself for a better sleep. 
- Sleep environment – Most people thing about this as mattresses, pillows, blankets, and the bed sheets. While these may be important, a comfortable sleeping environment also include a clean and tidy room. Arguably,the temperature,noise and the darkness of the room matters too. [33-38]So, examine yours to see how you can prepare a better sleeping environment for yourself.
- Balance Blood Glucose – While it is more commonly seen in patients with diabetes, nocturnal hypoglycemia (low blood sugar at night) can be another reason that wake a person up in the middle of the night apart from stimulants. So don’t starve to sleep and having complex carbohydrate may be a better option for stable blood sugar level throughout the night. [39,40,41]
- Pelvic Floor Muscles – One physical factor that can cause people to have frequent urination is weak pelvic floor muscles. This is in fact another common reason for people to get up to urinate in the middle of the night, and causes sleep disturbance. One way to manage and work on the pelvic floor muscles is to perform Kegel exercise, to help gain better control over the bladder. However, it is important to note that there are other medical conditions that can cause an overactive bladder that warrant medical attention and treatment.[42,43]
Hopefully, this article articulates to you the importance of sleep on our immune system and our general health. There are various ways that you can start to implement to give yourself a better sleep. However, please know that research on how to best improve sleep is still in progress and the reason for that is due to individual uniqueness,therefore not all of the tips above may work for you.[44,45] So for the time being, let’s create a routine that best fits your lifestyle and one that can benefit your well-being.
*Please note: Due to the novelty of COVID-19, there is no absolute research data being published in regards to the effectiveness of dietary or lifestyle interventions for its prevention or treatment. Your individual and unique circumstances during this challenging time are well respected and empathized.The above information / recommendations are not specific to COVID-19 and are not intended to replace medical consultation with your healthcare provider.
*Reminder: You should always seek medical advice immediately from clinic or hospital if experience signs and/or symptoms related to Covid-19.
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