Written by Matilda Greenacre
In the winter of 1964, 17-year-old Randy Gardener set the world record for the longest time a human has spent deprived of sleep, spending a total of 11 days and 25 minutes awake. Whilst 264.4 hours spent awake sounds like a productive use of time, even a single sleepless night hinders the proficiency of our brain and body function. An absence of sleep quickly takes impact on how you feel and behave, with the sleep deprivation causing: emotional irritability, a loss of concentration, and a weakened immune system.
EFFECTS ON THE IMMUNE SYSTEM
Sleeping for between 7-9 hours a night has been proven to enhance the efficiency of the immune system. Research was conducted by a group of American universities (1), in which 164 volunteers, all aged 18 to 55, were exposed to rhinovirus (the typical cause of the common cold). The volunteers had their sleep tracked in the weeks prior to the attempted infection and the experiment’s data concluded that those who consistently slept for under 5 hours were 4.5 times more likely to contract a cold than those who slept for 7+ hours a night.
In the unconscious state of sleep our muscle activity reduces, therefore, the muscles require less energy. This energy can instead be used for other tasks within the body, for example, the production of cytokines and white blood cells which are used within the immune system to aid cell communication and fight infection. This means that whilst we sleep our immune system is more capable of fighting off infection, for this reason increased hours of sleep decrease liability to short-term illness.
EFFECTS ON MEMORY
Human memory begins only 20 weeks after conception and an adult is believed to be capable of recalling between 20,000 and 100,000 words, however, the average adult’s short-term memory only lasts between 20-30 seconds. Humans commit information into long-term memory; this occurs during sleep. When we sleep newly acquired memories become consolidated meaning they can be recalled when awake.
In addition to negatively impacting the effectiveness of the immune system, a lack of sleep worsens your ability to focus during the day and this impairs your capability of learning effectively by up to 40% (reported by the Sleep Foundation). A diminished quantity of sleep not only weakens concentration but also declines the number of memories that can be formed and that are then remembered the next day. Throughout sleep new memory pathways are created which enable information to be stored within the hippocampus. The University of Lübeck in Germany conducted a study on the role that sleep plays in memory, the results evidenced that those who had a short nap of 40 minutes after attempting to memorize new information had a retention rate that is 25% higher than those who remained awake.
To live a healthy and balanced life we know that we must eat a nutritious diet and exercise regularly, however, the true importance of sleep is often neglected. Then human body’s natural circadian rhythm is often disrupted by blue light from technology, such as phones and computers, interrupting the body’s production of melatonin. A hormone released by the pineal gland that makes us tired. For this reason, it is suggested to turn of electronic devices one hour before bed to become drowsy and ensure a better night’s sleep resulting in a healthier wellbeing.
(1) Aric A Prather, et al; Behaviorally Assessed Sleep and Susceptibility to the Common Cold; Sleep; 2015 Sep 1;38(9):1353-9.
(2) Ines Wilhelm, et al; Sleep selectively enhances memory expected to be of future relevance; J Neuroscience; 2011 Feb 2;31(5):1563-9.