While we invest our energy each night calculating the hours of sleep we would get thinking that eight hours of sleep would energise us, we often forget what is more important is the quality of sleep.
The truth is that you can sleep for eight hours and might still be left feeling drowsy, fatigued, and lethargic. To feel truly rested and prepare the body for a new day, quantity is not the only thing that you should be considering.
Sleep is a vast topic. The right type of sleep for each person could even differ. It is first important to understand what a night of good sleep is.
Defining quality sleep
“Poor sleep quality and sleep deprivation can have many negative effects. These can be physiological, including increased risk for stroke, heart disease, and high blood pressure. Negative effects can also be psychological, such as increased irritability or development of anxiety or depression,” Danielle Pacheco from the Sleep Foundation says.
Many people think that sleep itself is just one long stage of unconsciousness. However, the body goes through four different stages of sleep. During these phases, our body temperature changes and so do our breathing patterns.
The stages are mainly divided into two parts: REM sleep and non-REM sleep. REM sleep is the fourth stage while the other three stages occur in non-REM sleep.
The final stage of non-REM sleep is what is commonly called deep sleep. It is also known as “slow wave sleep” and the first half of the night is spent in this stage. Up to 23% of the nightly sleep involves deep sleep and segments shorten every time we cycle through the stages.
Deep sleep is a time for the body to truly relax. The breathing slows down and the muscles, including the muscles in the heart, relax. Experts believe that this is the most crucial stage of the night as this stage serves the purpose of restoration, promoting growth and recovery.
“Sleep also contributes to human growth. For this reason, infants, children, and teens need more sleep than adults. People of all ages need sleep to prevent sickness or recover from illness or injury,” Pacheco adds.
If this stage, that is, your deep sleep (and REM sleep) is disturbed, the hours you sleep do not matter. An eight-hour sleep with a disrupted REM episode can result in lethargy and affect your ability to function properly the next day.
“There are other sleep disorders that can cause sleepiness despite seven to eight hours of sleep, including sleep apnea, narcolepsy and a delayed sleep phase,” says Dr Susheel Patil of the Johns Hopkins Sleep Centre, adding that interruptions during the night are common.
Signs you are not getting good sleep
While of course, it is hard to point out what kind of sleep you are getting each night, there are some telltale signs in your behaviour the next day that can help you identify the quality of your sleep.
“A person’s symptoms can depend on the extent of their sleep deprivation and whether it is acute or chronic,” says Eric Suni, previously an information specialist for the National Cancer Institute.
Here are some behavioural signs:
Waking up exhausted: If you did not cook and clean while you were asleep, why would you wake up feeling tired? Waking up exhausted is the most common sign of disrupted deep sleep.
Naps during the day: Whether planned or unplanned, if your eyelids are drooping the entire day or at least during some hours, it could be because you did not get restful sleep at night. Your body might be begging for actual rest and not just a shut-eye at night.
Lack of concentration: Alertness is significantly impacted by sleep. The inability to focus and concentrate on daily tasks during the day could be because of the sleep quality last night. If you are not well-rested you may end up underperforming at work.
Irritability: Sleep deprivation can lead to prominent and unavoidable irritability. Are you feeling bothered by things that do not bother you? Notice if you are impatient and losing your temper more quickly than usual.
Bad memory: Just like the ability to concentrate is affected, other cognitive functions can also be impacted. One of them is memory. Short-term, working memory may clearly be affected and you might feel yourself “lagging” the entire day.