What happens in our bodies when we don't get enough sleep?
In the 1990s, nearly 70% of Americans were getting seven to eight hours of sleep a night. Nowadays, in some areas of the US, as many as 50% of the population is considered sleep deprived, with about 30% getting less than six hours of sleep. About 50 to 70 million Americans are considered to have a sleep disorder.
Insomnia is the most common specific sleep disorder, with short-term issues reported by about 30% of adults, and reports of chronic insomnia in about 10% of adults. Because it's associated with many other diseases, as we will see, the effects of sleep loss and sleep disorders represent an under-recognized public health problem.
So, what are causes of sleep deprivation? Surprisingly, the most common cause is actually not going to bed. People think they need to be productive, or that sleep is unnecessary. Poor sleep hygiene and stress play a significant role. In a recent poll, 65% of Americans felt that they were losing sleep due to stress, and among those, 32% that they were losing at least one night per week.
Much lower down the list are people who actually have a sleep disorder, or people with brain disorders that affect the architecture of sleep. General illness also contributes to poor sleep. Sleep apnea, for example, is often associated with obesity, and menopause causes hot flashes and thus poor sleep. As many as 50% of people with sleep apnea also have undiagnosed diabetes. Chronic pain or digestive disorders also inhibit a good night's sleep. People who are sleep deprived typically need an alarm clock to wake up. They fall asleep as soon as they hit the pillow, whereas well-rested non-sleep deprived people should take an average of 15 minutes in bed to fall asleep. Other signs of sleep deprivation are napping easily, being irritable, falling ill easily such as catching colds. The most common cause of sleep deprivation is chronic insomnia.
This simply means, not getting enough sleep at night to feel rested the next day. Often these patients use sleep aids in the form of over-the-counter prescription drugs to fall asleep. Insomnia can be caused by the inability to fall asleep, or waking up in the middle of the night and having trouble going back to sleep, or even just waking up too early. Obstructive sleep apnea is another major public health burden, because it can increase the risk of many other diseases like hypertension, heart disease, stroke, and depression. A patient with obstructive sleep apnea essentially stops breathing during sleep.
This can be due to several things, either obesity or an anatomical problem in the upper airway, causing the airway to collapse during sleep. These repeated apnea episodes can happen a hundreds of times throughout the night causing little micro arousals that result in a non-restful sleep. You can screen yourself for sleep apnea by taking the STOP-Bang Questionnaire. It essentially asks you a list of questions including your weight, whether you snore, if you feel fatigued during the day, whether somebody has witnessed you stopping breathing, and so on. This will give you a score that correlates with the risk of sleep apnea. Another scale is the Epworth scale that looks for signs of a sleep disorder in general. Both questionnaires can be found in this week's reading materials.
So, how do we study sleep in the medical world? We have at our disposal the classic sleep study.
An individual volunteers to go to the sleep lab and gets hooked up to several wires. It includes EEG monitoring to look at brain waves, EKG to monitor the heart, and pads placed on the legs and the chin to monitor muscle activity. We measure oxygen saturation as well, which is especially useful in sleep apnea. There are also wearable accelerometers, just like your smartwatch that count your steps. These are lightweight, small, and much less intrusive than a sleep study. These measure the duration and frequency of your sleep activity, and especially your leg movements.
The Centers for Disease Control and Prevention or CDC provided statistics of sleep deprivation in the US. These statistics are eerily similar to the data on obesity, diabetes, and even stroke in the US. This is not the product of sheer coincidence. Sleep deprivation is associated with an increase in hypertension, heart disease, weight gain, and insulin resistance or diabetes. Another CDC publication illustrates the prevalence of mental distress and depression in the US. So, sleep deprivation is not just about feeling groggy, it negatively affects your entire body. In addition to these chronic diseases, sleep deprivation is also associated with poor quality of life, daytime dysfunction, higher mortality, and higher economic costs due to lost productivity, and injury to self or others.