John Cordle, a highly experienced captain in the American Navy was commanding a routine training exercise in the Baltic Sea, helming USS Oscar Austin, a guided-missile destroyer, with three other destroyers behind it. Cordle had been operating without sleep for 36 hours. As the ship settled into its passage, Cordle tottered, trying to stay awake. Low lights and silence—he dozed off.
His navigator woke him up only to tell him that the destroyer had lost its position. Cordle was dazed and fatigued. He ordered the destroyer to be slowed down. But there were three more ships behind him that needed to be informed as well and in time.
“I let myself get so tired that when the crew really needed me to step in and make a decision, I was too tired to understand what was really going on,” Cordle tells the Rand Review. “There’s this perception that you can force yourself to just suck it up and get through it. But it’s like being drunk: Your brain shuts down.”
Why does good sleep matter so much? According to a study by RAND, the cost of employees showing up at work without proper rest is a staggering $411 billion, and 1.2 million annual working hours are lost in productivity every year. When we sleep well, our productivity at work or home skyrockets. This is because sleep is an important source of energy. Lack of it can affect almost every working organ and tissue system in our body.
Apart from carrying out multiple involuntary functions, our body is also known to repair itself and clear out toxins while we are asleep. Not getting enough sleep enough impairs this critical repair work. It can influence your mood, energy, focus, and clarity, as well as affect the neural pathways to perceive, remember, and respond. A lack of sleep has also been linked to increased risk of diseases like high blood pressure, cardiovascular diseases, and mood disorders.
Sleep occurs in two stages—REM (rapid eye movement) and non-REM. There are specific brain waves and neural activity connected to each of them. We move through both stages several times in the span of a night, spending a long time in REM toward the morning.
Stage one, non-REM, is the shift from a wakeful state to light sleep. During this stage that lasts up to a few minutes, our heart rate, brain waves, and breathing slow down. This is followed by the second stage of non-REM sleep, defined by light sleep, even slower heartbeat and breathing, and muscle relaxation. Here the body temperature is also reduced. The brain waves slow with spurts in electrical activity. The next stage of non-REM sleep is where your sleep deepens, with brain waves, heartbeat, and breathing at their slowest. It is usually difficult to wake up a person during this stage.
After these four stages, one enters REM sleep—about 90 minutes after hitting the hay—where dreams are experienced. Thankfully, nature has put in place a mechanism for your muscles to be paralyzed at this stage, so you do not start moving your body as you dream. Here, your eyes move rapidly from side to side, brain wave activity recurs and resembles that of a waking state, breathing is faster, and heart rate and blood pressure rise.
Factors that Impact the Sleep Cycle
Age. How much time we spend in REM sleep varies as we age. Infants and newborns spend much longer—in fact, they move into REM almost immediately after falling asleep. As we age, we spend less and less time in REM, and our sleep becomes more fragmented.
Amount of sleep. If sleep is insufficient or irregular, it can have an impact on one’s sleep cycle and the time one spends in the REM stage.
Alcohol and drugs. The use of alcohol and drugs can also have an effect, by first delaying and then prolonging the time spent in REM. This can induce lethargy and sleepiness during the day. But more dangerously, drinking yourself to sleep every night can cause dependence and demand consumption of incrementally more quantities of alcohol to be sedated enough to sleep.
Light. Light can affect sleep by disrupting our biological clock, an internal guide to sleep-wake timings based on the cues from the environment such as light and temperature. It controls and guides the circadian rhythm, synchronizing it with our environment. Our circadian rhythm controls all the bodily functions that cause one to feel sleepy at a particular time or wake up at a particular time, even without an external alarm. Specific cells in our retinas receive light falling on them and send signals to the brain about the time of the day, preparing our body to either wake up (when there is light) or go to sleep (when it is dark).
The invention of artificial light has had a significant impact on this natural mechanism. As a result, exposure to light post-evening potentially disrupts the biological clock, as our brain remains alert even when it is late and dark outside when naturally we should be falling asleep. (Think television, computer, or phone screen.)
Jet lag and change in shifts. While we are usually guided by our inner biological clock about when to sleep or wake up, changes in our external environment while traveling across time zones or working late-night shifts can impact our sleep cycle. When we travel to another time zone, our biological clock—which broadly works on a 24-hour cycle—tries to catch up with the changes in the external environment. It may be time to sleep according to what our body clock is used to, but it may be daytime where we are. This can cause fatigue, sleepiness, and tiredness in the body until our biological clock has adjusted to the new time zone. Similarly, people who work late-night shifts may feel sleepy at night and struggle to fall asleep during the day until their biological clocks have adapted to the new sleep schedule.
Sleep-related illnesses. Sleep disorders such as sleep apnea, restless leg syndrome, or even diabetes can affect the quality of your sleep by not allowing your body enough rest in REM stages. Here are some natural ways to treat insomnia.