How Sleep Affects Mental Wellbeing and Focus

Sleep is when your brain processes and stores information from the day, repairs, resets, and prepares itself—and you—to be
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Stressed woman needing help sleeping at night
Sleep is when your brain processes and stores information from the day, repairs, resets, and prepares itself—and you—to be ready for the next day. Your mental wellbeing is affected by the intricate interactions between the different parts of the brain, that happen while you sleep. However, data show that sleep loss is becoming more prevalent than ever, with over 1 in 3 Americans not getting enough sleep on a regular basis.1

Keep reading to learn what happens while you sleep that affects your mental wellbeing every single day.

How Sleep Affects Your Mental Wellbeing

Sleep Supports Healthy Brain Function

Your brain works nonstop every single day to support you. While you sleep, your busy brain cells finally get some time for self-care. Every night they restore their internal balance, or homeostasis, and strengthen their connections (synapses), with other brain cells. This process, which happens during slow wave sleep phases, improves neuroplasticity – the brain’s ability to coordinate efficient communication within and between brain areas, so it can be resilient and adapt to change.2

Sleep Helps the Learning Process

While you sleep your brain takes new information and stores it in the appropriate areas. That way tomorrow, the next day, and a year down the road you can use the skills you learned today at school or on the job. The process of creating long-term storage so that new information and skills become permanent happens during a portion of sleep in which the brain waves are at their slowest.3 This wave pattern, known as delta waves, occurs during deep, non-dreaming sleep.

Sleep Helps Maintain Emotional Balance

While your brain is storing the day’s events, it is also processing their emotional significance. This happens primarily during REM sleep and involves coordination between the primitive emotional center of the brain called the amygdala and the outer cortex.4

How Sleep Affects Mental Health

Not getting enough quality sleep has rippling effects throughout the brain and body that may impact your mental health.

Sleep supports a healthy emotional state and decision-making abilities.

Getting enough sleep each night is essential to the brain working optimally and processing energy in a way that supports you best. With the help of an advanced imaging technique called positron emission tomography (or a PET scan), we can see how the brain alters its use of energy when you don’t get enough sleep. In research studies, PET studies have shown hyperactivity in the brain’s arousal and emotional centers and suppressed activity in the executive, decision-making areas in individuals with impaired sleep.5

Sleep Supports Healthy Testosterone Levels.

Your central nervous system and endocrine system are so closely interconnected that the two are often referred to as a singular, neuroendocrine system. One of the ways a lack of sleep impacts endocrine function is by lowering levels of testosterone in both men and women. In the brain, testosterone enhances the activity of GABA (the “relaxing hormone”) and serotonin (the “happy hormone”), the two most important brain-calming neurotransmitters.6

Sleep Helps Maintain Production of Brain-Activating Hormones.

When you get too few hours of sleep, your brain stays active and alert. This requires increased production of brain-activating hormones, like norepinephrine and cortisol, which mobilize blood sugar to keep your brain and body going in the short term.7

How Sleep and Stress Are Connected

Sleep Helps Regulate the Stress Response System

Sleep Gives Your Brain Time to Reset Stress Levels.

When you don’t get enough sleep your levels of the brain-activating hormones norepinephrine and cortisol stay elevated to keep your brain awake. Normally, cortisol is present at higher levels in the morning, which helps you get out of bed to start your day, peaks around midday, and then declines to its lowest level during sleep. However, after a night of poor sleep, your brain requires more of these hormones to stay alert and functioning during the day, which keeps it in a more excited and excitable state. That’s why after a night of poor sleep, you may find it more difficult to keep your brain on task.4, 7

How Sleep and Memory Are Connected

A good night’s sleep helps you respond quickly and accurately in day-to-day situations.

Throughout a typical day, you make many decisions, small and large. During the decision-making process, your brain quickly accesses stored memories and then makes a best-guess choice between all of its options based on the gathered information. The time it takes to access these memories, gather enough information, and arrive at a decision is known as “drift-rate.” Sleep deprivation affects drift rate, resulting in both longer time to make decisions and errors in arriving at the correct choice.8

Sleep Gets Rid of the Energy Waste Your Brain Doesn’t Need.

Your brain uses more energy than any other organ in your body and it’s even a major energy guzzler even while at rest.9 And cells that consume a lot of energy produce a lot of metabolic waste. Sleep can get rid of some of those cellular waste products, called free radicals. Lack of sleep decreases the amount of time your brain has for internal housekeeping. As a result, free radicals build up, which can affect nerve function and memory storage.2

A good night’s sleep gives your brain time to consolidate and organize memories.

When you learn something new during the day, that information is placed in temporary storage, somewhat like a blurry image. Then when you go to sleep, your brain can process and sort through the information. Part of the process of making memories permanent requires streamlining, or “pruning” the temporary synaptic connections that make up the blurry image into an efficient pathway within the brain. When you’re not sleeping enough, you have less ability to consolidate memory in this way.10

When it takes you longer to sort through memories and learnings, it can affect your workflow, making it harder to focus and work efficiently and productively.

How A Lack of Sleep Affects Focus and Productivity

It Decreases Motivation

A bad night’s sleep leaves you feeling tired and less alert the next day. Just thinking may seem like hard work. And the longer you have to stay focused on a task the greater performance is affected.11 In one study, sleep-deprived participants consistently chose less challenging tasks than a well-rested control group.12 Part of the reason for the lack of motivation is that sleep deprivation activates areas of the brain that seek a sense of reward (what will I gain from doing this?) and reduces activity in a brain area called the insula, that helps facilitate high-level attention and decision-making.11, 12 As a result, your brain seeks a greater reward while at the same time is less able to perform well.

It makes it easier to doze off

Do you ever find yourself snapped awake, before you even realize you fell asleep? If you’re really exhausted, such as near the end of work after a night of poor sleep, and you find yourself nodding off or staring into space, this is called “microsleep”. These brief periods only last a few seconds, but they are involuntary and can interrupt your focus. Other signs of microsleep include inability to keep your eyes open and very small pupil diameter. Microsleep can decrease work productivity for some workers and lead to compromised ability to stay alert for those in labor-intensive professions.11, 12

As you can see, sleep is so important to your overall health. Your brain uses an incredible amount of energy all day, every day. Make sure you’re thanking your brain by giving it what it really wants—a good night’s sleep, every night.

How to Encourage Healthy Sleep Hygiene

Establishing healthy sleep habits is essential to your overall health. Promoting a healthy lifestyle goes hand-in-hand with ensuring that you are not only getting enough sleep, but also getting quality sleep.

ZzzQuil is here to help you on your journey to your best sleep. Sign up for ZzzQuil’s Better Sleep in 1-2-Zzz to learn more about how you can optimize your sleep routine.


  1. US Centers for Disease Control and Prevention (CDC). Data and Statistics-Short Sleep Duration Among US Adults. Available at:
  2. Atrooz F, Salim S. Sleep deprivation, oxidative stress and inflammation. Adv Protein Chem Struct Biol. 2020;119:309-336. doi:10.1016/bs.apcsb.2019.03.001
  3. Walker MP. The role of sleep in cognition and emotion. Ann N Y Acad Sci. 2009;1156:168-197. doi:10.1111/j.1749-6632.2009.04416.x
  4. Goldstein AN, Walker MP. The role of sleep in emotional brain function. Annu Rev Clin Psychol. 2014;10:679-708. doi:10.1146/annurev-clinpsy-032813-153716
  5. Riemann D, Krone LB, Wulff K, Nissen C. Sleep, insomnia, and depression. Neuropsychopharmacology. 2020;45(1):74-89. doi:10.1038/s41386-019-0411-y
  6. Hanson JA, Huecker MR. Sleep Deprivation. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 26, 2021.
  7. Copinschi, Georges. “Metabolic and endocrine effects of sleep deprivation.” Essential psychopharmacology 6 6 (2005): 341-7 .
  8. Squire LR, Genzel L, Wixted JT, Morris RG. Memory consolidation. Cold Spring Harb Perspect Biol. 2015;7(8):a021766. Published 2015 Aug 3. doi:10.1101/cshperspect.a021766
  9. Ratcliff R, Van Dongen HPA. The effects of sleep deprivation on item and associative recognition memory. J Exp Psychol Learn Mem Cogn. 2018;44(2):193-208. doi:10.1037/xlm0000452
  10. Squire LR, Genzel L, Wixted JT, Morris RG. Memory consolidation. Cold Spring Harb Perspect Biol. 2015;7(8):a021766. Published 2015 Aug 3. doi:10.1101/cshperspect.a021766
  11. Massar SAA, Lim J, Sasmita K, Chee MWL. Sleep deprivation increases the costs of attentional effort: Performance, preference and pupil size. Neuropsychologia. 2019;123:169-177. doi:10.1016/j.neuropsychologia.2018.03.032
  12. Massar SAA, Lim J, Huettel SA. Sleep deprivation, effort allocation and performance. Prog Brain Res. 2019;246:1-26. doi:10.1016/bs.pbr.2019.03.007
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