Sleep remains a very mysterious body function. It preoccupies nearly a third of our lifetime, yet scientists and physicians actually understand very little about how sleep works. The mechanisms, molecular pathways, and downstream effects of sleep are actively being explored and investigated by modern scientists. Recent studies suggest that sleep has a much larger role in our daily functioning than we previously thought, and this perhaps creates growing risk factors considering that the CDC reports a third of adults sleep less than seven hours a night.
What We Do Know
While we often think of sleep as our bodies shutting down and becoming inactive for the day, quite the opposite is occurring in the mind. During sleep, our brains are very much in an active state, complex and different than the state of an awake brain.
The brain sleeps in one stage of light sleep, three stages of slow-wave sleep (SWS), and one stage of rapid eye movement (REM). A complete sleep cycle encompassing all 5 stages usually last for 90 to 110 minutes. SWS gives us deep, slow breathing sleep and preoccupies most of our sleep time, and REM interestingly gives us a temporary muscle paralysis and irregular breathing and is when our dreams occur.
We know that sleep correlates with functions of clearing toxins from the brain and reinforcing memory and new information taken in from the day. Sleepiness is caused by a build up of adenosine in our blood as we are active during the day, and during sleep this chemical is broken down. However, the functionality of sleep is speculated to extend much further. Sleep is continuously correlated with moderating behavioral functions of mood and appetite, and sleep-deprivation is correlated with decreased immunity to disease and lower life spans.
What Current Studies Are Investigating
Here are some quick summaries on some recent interesting studies:
The Institute of Human Nutrition at Columbia University Medical Center found that daily intakes higher in fiber and lower in saturated fats and sugars yield better sleep and faster rates of falling sleep. Fiber is correlated with more deep SWS sleep, saturated fat is correlated with less SWS sleep, and sugar is correlated with increased arousals from sleep.
Tel Aviv University published in the Journal of Neuroscience that sleep deprivation causes loss of neutrality and impairment of judgement in emotional responses. In essence, loss of sleep causes the loss of ability to sort out levels of important information, which can also result in anxiety from emotional sensory overload.
A new study published in Diabetologia made a correlation between sleeping problems and an increased risk for developing type 2 diabetes in women. Another study by the University of Colorado shows that after four nights of sleep restriction, subject insulin sensitivity decreased by 23% and diabetes risk increased by 16%.
The University of Chicago Medical Center published a study in the journal SLEEP that found that sleep loss increases a chemical signal in our endocannabinoid system that highers the desire for for sweet or salty, high-fat snack foods and increases a person’s impulsivity to indulge on them. A person likely burns an extra 17 calories for every extra hour they stay up at night, but will likely take in four times the amount the next day as a result.
A study published by Duke-NUS Medical school in the journal SLEEP shows that a week of 5 hour sleeping nights yields significant reduction of attention, processing, and alertness that aren’t negated after two nights of recovery sleep.
As we can see, sleep involves and is involved in very complex physiological parameters. It’s not just recuperation for the mind, but also a function suggestively intertwined with diet, exercise, immunity, and mental health emotionally and cognitively.
Studies are continuously being conducted every day to get to the bottom of the sleep mystery. If you’re interested in contributing, the American Sleep Apnea Association and IBM recently launched a mobile app called SleepHealth, a new crowd-sourced citizen science project on sleep. It’s purpose is to help users take learn about sleep health, while also contributing to the first sleep data repository and to current research being conducted by scientists.