When someone’s in a foul mood, we might joke that they “woke up on the wrong side of the bed”. But is that all there is to sleep?

With 4 out of 10 Singaporeans not sleeping enough on weekdays, it might seem like sleep isn’t really that important. Some of us drink coffee to perk ourselves up, feel unaffected emotionally, and work from home (i.e., there is no need to socialise with co-workers or bosses). Even if so, we’re here to remind you that sleep does affect us, even if it seems like it doesn’t!

What Happens When We Sleep

Sleep comprises 4 stages: N1, N2, N3, and REM (rapid eye movement). Most of us might have heard of REM and that’s when we get to experience dreams, but did you know about the others?

We would typically go through 4 to 6 sleep cycles a night, with each cycle ranging anywhere from 1 to 2 hours.

What Is Affected When We Don’t Sleep Enough

Sleep stages vary in duration during our sleep, and sleeping short of what is recommended can adversely impact our cognitive abilities.
Regardless of stimulants (such as coffee), we might find ourselves making more mistakes. Sleep deprivation brings about a reduced ability to focus, which can result in “running on autopilot” and poorer decision-making. Here’s how and why.
Firstly, N2 and N4 stages lengthen with each successive cycle into the night. N4 (REM) is not experienced until we have been asleep for approximately 90 minutes! If we sleep lesser overall, the proportion of time we are in N2 and N4 stages would be less than the estimated of 45% and 25% respectively (the proportion in the sleep cycle above are averaged across sleep cycles). Our brain would have fewer opportunities for memory consolidation. We may then find ourselves more prone to forgetting events or struggling to commit to memory something we learnt the previous day.
Conversely, N3 shortens in the later cycles of sleep. If we sleep lesser overall, there’s a greater chance that we might wake up in N3. Granted, it should be harder to naturally wake during N3 (it is called “deep sleep” for a reason!), but with our alarms blaring away, we could very well still wake then. Waking up during this stage may result in “mental fogginess” for 30 minutes to an hour – many of us could probably relate to the feeling of waking up groggy and struggling to get our gears going.
tldr; A shorter sleep affects our ability to consolidate memories, impairing our ability to learn. There is also a greater chance of waking with “mental fogginess” when our sleep is short.
Most of us would certainly have experienced at least one night of poor sleep (think back to the day before a presentation or the release of results of a major examination). How did you feel the next day?
A lack of sleep or poor sleep quality can cause us to feel lethargic and experience difficulties staying awake the following day. When prolonged, inadequate sleep can leave us constantly feeling fatigued and spent, in turn affecting our overall well-being and lowering our quality of life.
A lack of sleep can impair our body’s stress response system. The elevated levels of the stress hormone cortisol could cause us to find daily stressors more challenging than usual, and lead to greater and more intense experiences of stress.
In a survey of 1,950 American adults in 2013, adults who slept fewer than eight hours a night reported higher stress levels than those who slept at least eight hours a night.
A lack of sleep has also been found to result in increased secretion of the hormones: dopamine and serotonin. Sounds familiar? That’s right!
Dopamine and serotonin are usually called the “happy” hormones and they are both involved in regulating our emotions! An imbalance in their levels can disrupt our ability to regulate our moods.
Hormone-science aside, think back to the last time you were worn out. Didn’t everything just seem a bit more irritating? Did you find yourself tearing up more easily?
Simply put, sleep deprivation can result in increased emotional sensitivity: reactivity to unpleasant emotions is enhanced while reactivity to positive events might feel subdued. There’s a reason for the saying “woke up on the wrong side of the bed” after all!
When we’re already struggling with what little energy we have and our own mood, finding energy to successfully navigate social interactions can be difficult.
We may have less empathy for others, may be more willing to engage in conflict rather than put in the effort to find a compromise, or may simply withdraw from social interactions completely.
All in all, as social interactions get more challenging given the reduced capacity because of poor sleep, one could more likely feel frustrated, angry, and stressed. In the long run, strained relationships would also translate into us having less social support to tide us through our struggles, and it can feel particularly isolating.

Adding It All Up

Does sleep sound important enough yet? We commonly hear about the lack of sleep leading to physical ailments such as high blood pressure and heart diseases, and that’s the case for our mental health too! With how sleep deprivation affects us in the ways above, you can imagine how there is also an increased risk of developing mental health disorders.

Studies have found that those with sleep difficulties are more likely to feel stressed, ruminate, develop depression, anxiety, post-traumatic stress, eating disorders, and experience psychotic episodes.

For individuals who are already struggling with mental health difficulties, inadequate sleep can exacerbate symptoms and hinder therapeutic progress. Conversely, the greater the sleep quality, the lower the likelihood and severity of such outcomes.

Contrary to popular belief, sleep is not for the weak. Sleep makes us strong enough, emotionally, intellectually and physically, to tackle our challenges and daily stressors. “Catching up on sleep” doesn’t work the same as sleeping the recommended amounts per night. There is a limit to how much we can undo the adverse effects of long-term sleep disturbances.