Sleep is the single most effective thing we can do to reset our brain, augment our immune response, and maintain optimal physical and mental health. Despite this, modern-day living does not always embrace the importance of sleep. Although individual sleep needs vary and depend on age, health and activity level, we have been told to strive for 7-9 hours of sleep per night. But have you ever stopped to ask yourself “why is sleep so important?”

Sleep and physical health

Sleep is a vital component in our body’s restorative processes. In fact, muscle repair, protein synthesis, and tissue growth all happen while we sleep. Another critical function of sleep is the removal of damaged and mutated cells. As such, sleep has a critical anti-cancer role. Further to this, insufficient sleep suppresses the production and release of immune cells, such as cytokines and T cells (responsible for fighting infections and inflammation). One study showed that sleeping less than 7 hours per night increased participants’ risk of developing cold and flu symptoms 3-fold compared with participants obtaining at least 8 hours of sleep, while another study reported that short sleepers are 4x more likely to catch a cold. 

Insufficient sleep has also been linked to certain diseases and medical conditions, such as high blood pressure, heart and kidney diseases, type II diabetes, and obesity. Moreover, sleep has a role in removing toxins from the brain via the glymphatic system. The build-up of one such toxin, beta-amyloid, has been linked to Alzheimer’s Disease.

Sleep and mental health

We have all experienced what it’s like to wake up on the wrong side of the bed and continue through the day tired and irritable. This is because sleep and mood are closely connected. Unsurprisingly, sleep disturbance is a common symptom among individuals diagnosed with depression, anxiety, and stress. Research has shown that a night of poor sleep increases the risk of experiencing symptoms of:

• Depression (21%)
• Hopelessness (24%)
• Anger (24%)
• Anxiety (25%)
• Desire to self-harm (25%)
• Suicidal ideation (28%)

Notably, treating the sleep disorder may help to alleviate symptoms of psychological distress, and vice versa.

Sleep and productivity

Obtaining good sleep quality and quantity each night has been linked to superior concentration, productivity, cognition, and memory consolidation the following day. Specifically, neural pathways responsible for retaining information and learning new skills are reinforced while we sleep. This has considerable implications for academic performance among students and workplace outputs among employees.

Sleep and athletic performance

Sleep quality and quantity are particularly important for active individuals. Believe it or not, some elite athletes, like Roger Federer and LeBron James, sleep for 12 hours per night, while Usain Bolt, Venus Williams, and Maria Sharapova sleep up to 10 hours per night!

Studies have consistently shown that poor sleep can have the following consequences for athletic performances: 

• Slower average and total sprint times
• Reduced accuracy
• Quicker time to exhaustion
• Slower reaction time
• Decreased strength and aerobic output
• Difficulty learning and decision making, leading to more mental errors
• Increased risk of injury and illness

In summary, sleep is vital for overall health, wellbeing, cognitive functioning, and athletic performance. The next time you hear the saying: “Don’t lose sleep over it”, it may be wise to listen.

References:

Sleep and immune function
Sleep habits and susceptibility to the common cold
Behaviourally assessed sleep and susceptibility to the common cold
Lack of sleep harms college students’ mental health
Sleep and athletic performance: the effects of sleep loss on exercise performance, and physiological and cognitive responses to exercise