Sleep can sometimes be viewed as almost a luxury in modern life—but in fact, it is a biological necessity, and one of the most critical factors influencing mental health. This article explores how much sleep you should get, by age, why sleep cycles and stages matter and how to account for them when planning our bedtime, and describes the major mental-health risks associated with sleeping too little.
Mental Health Risks from Sleeping Too Little
Let us begin with the “why”, as there are good reasons to want adequate amounts of sleep. There is substantial scientific evidence that insufficient sleep—or chronically short sleep—can elevate the risk of a range of mental-health problems. A good review of these is available from the National Heart, Lung, and Blood Institute. Some of the major issues linked to inadequate amount of sleep include:
Distress, depression and anxiety
Lack of sufficient sleep can cause these harmful effects in both adults and adolescents. For example, a large adult U.S. study [1] found that adults sleeping 6 hours or less per night had about 2.5 times the odds of reporting “frequent mental distress” compared to those sleeping more than 6 h.
For adolescents, a longitudinal study [2] found evidence that chronic sleep deprivation in young women (but not consistently in young men) was associated with higher depression scores at follow-up. In another study based on Florida high-school data: over 75 % were sleeping less than 8 h on a school night; those insufficiently rested were significantly more likely to report depressive symptoms, suicidal ideation or planning. [3]
Importantly, there is a reciprocal association between sleep disturbances and depression, which may result in a cycle in which disrupted sleep exacerbates depressed symptoms, which in turn influences sleep quality. [4]
Cognitive, emotional regulation, and brain-function impact
Sleep deprivation has been shown to undermine attention, decision making, and emotional regulation. The U.S. National Heart, Lung, and Blood Institute states that sleep deficiency affects “how well you think, react, work, learn, and get along with others.” [5] Sleep stage disruption and fewer full cycles appear to mediate mood and cognition effects.
What are the mechanisms linking short sleep to mental‐health problems
- Emotional regulation: reduced REM or disturbed sleep increases reactivity of the amygdala (emotion center) and decreases prefrontal-cortex regulation.
- Memory and learning: sleep supports memory consolidation; impaired sleep undermines this and may affect self-esteem or cognitive resources.
- Inflammatory & physiological stress: sleep loss increases cortisol and inflammatory cytokines, which are implicated in depression and anxiety.
Can sleeping too long be harmful to mental health?
Interestingly, some studies suggest both too little and too much sleep are associated with elevated risk of mental-health issues. This seems to be most prominent in older adults, especially those showing signs of depression [4]. Thus, while the focus here is on insufficient sleep, in some cases excess sleep might also flag underlying problems or contribute to them.
Mental health implications
Given the associations, consistent insufficient sleep (especially if compounded by disrupted cycles or poor sleep quality) should be viewed as a modifiable risk marker for mental-health problems. For clinicians, researchers and individuals alike: improving sleep is a first-in-line preventive approach for mood disorders, anxiety and cognitive decline. With this in mind, let us cover the recommendations for a healthy sleep duration.
Recommended Sleep by Age
Sleep needs change markedly across the lifespan. While individual variations exist, major organizations and reviews provide consensus guidelines. According to the National Institute of Neurological Disorders and Stroke, the amount of sleep people need depends on several factors, including their age, individual requirements, and whether they have been getting adequate sleep.
- Infants and toddlers: According to the consensus statement [6] from the American Academy of Sleep Medicine (AASM), infants aged 4 months to 12 months should sleep 12–16 hours per 24 h including naps; children 1–2 years 11–14 h; children 3–5 years 10–13 h; children 6–12 years 9–12 h; and teenagers (13–18 years) 8–10 h.
- Teenagers: Many guidance sources use 8–10 h for ages 13–18. For example the U.S. National Institutes of Health’s fact sheet notes teens 13–18 should sleep 8–10 h.
- Adults (18–64 years): Most adult-sleep reviews suggest 7–9 hours per night for optimal health. For example, a recent review states adults 18–64 “typically require 7 to 9 hours per night for optimal health” [7] .
- Older adults (65+): Sleep needs may remain similar (7–8 h) though sleep quality often declines; some guidance suggests 7–8 h is adequate for older adults.
Beyond raw hours, it matters whether sleep is continuous, high quality, and aligned with circadian rhythm—but more on that shortly.
Failing to meet these ranges—or persistently sleeping well below them—is increasingly associated with poorer mental‐health outcomes as already discussed.
Why Sleep Cycles and Sleep-Stage Architecture Matter
It is not just how many hours you sleep, but how you sleep since the time we spend sleeping is composed of repeating cycles of two broad phases [9]. First, there is non-rapid eye movement sleep (NREM) with stages N1, N2, N3 (sometimes counted as stages 1-3 or 1-4 depending on scheme). Second, we also experience rapid eye movement sleep (REM).
Each full cycle lasts about 90–120 minutes in adults; across a typical 7–9 h night you might complete 4–5 cycles. In each cycle one goes through light sleep (N1/N2), deep (slow-wave) sleep (N3) and then REM sleep.
Why these stages matter
Deep NREM (slow-wave) sleep (stage N3).
This stage is particularly restorative: it supports brain and body repair, immune function, and memory consolidation.
REM sleep
Often associated with dreaming, REM also plays a key role in emotional regulation, memory processing, and mood. Lack of REM is linked to increased emotional reactivity and worse mental‐health outcomes.
Cycle integrity
When you persistently cut short sleep (e.g., wake up early), you may truncate later cycles, meaning less REM or less deep sleep. That can degrade the restorative benefit of sleep beyond just fewer hours.
The sleep-mental-health link via cycles
Poor sleep stage architecture (for example fragmented sleep, fewer complete cycles) is associated with mood dysregulation, impaired memory and learning, and increased risk of depression and anxiety [8]. Thus, achieving the recommended hours is only part of the story; maintaining stable sleep timing, reducing disruptions (apnea, wake awakenings) and preserving full cycles is also key for mental health.
Practical Recommendations for Healthy Sleep
To maintain your mental health via good sleep, consider the following points:
1. Aim for the recommended hours by age.
In broad terms these are, for teenagers: ~8–10 h; for adults: ~7–9 h; for older adults: Older adults: ~7–8 h. If you’re consistently sleeping significantly less than the recommended number of hours, your mental health may be at increased risk. For detailed help with scheduling, including for young children and adolescents, use a scientifically based sleep calculator. It will help you set your bedtime so you can get the necessary hours of sleep.
2. Protect full sleep cycles and good stage structure.
The best way to achieve this is to have a consistent bedtime, weekends included. Ideally, these would be accompanied by consistent wake up times. Reducing sleep interruptions by minimizing loud noises, light exposure, and having an appropriate temperature level should help get quality sleep. Also avoid alcohol, caffeine, heavy eating, and stimulating screens close to bedtime as they disrupt REM sleep and N3.
Daytime physical activity can be beneficial if not too close to bedtime.
3. Prioritize sleep quality, not just quantity.
Fragmented sleep with frequent awakenings can reduce deep and REM stages. Sleep disorders such as obstructive sleep apnea may greatly erode cycle integrity. To address this, seek evaluation if snoring, pauses, or daytime sleepiness occur.
4. Make a routine to support sleep architecture.
Just like small children need their routine to fall asleep, teenagers and adults typically benefit from having a wind-down routine. For example, it could consist of light reading, low light, or another calm activity that you do before bed.
5. Monitor sleep debt and pattern.
Repeated nights of short sleep accumulate a “sleep debt” that impairs cycles and might increase mental-health risk. If you find yourself frequently waking in the night, feeling unrefreshed, or requiring long recovery sleep on weekends—those are risk signs and you may need to take action before they take a toll on your mental health.
Summary
Sleep is not optional when you need robust mental health. Not only should you get the right number of hours of sleep (which varies primarily by age) but it should also be high-quality sleep, preserving natural cycles of NREM and REM.
Sleeping too little over extended periods of time, especially if sleep architecture is disrupted, carries elevated risks of depression, anxiety, cognitive impairment and emotional dysregulation. The good news is that sleep is modifiable. By treating sleep as a priority rather than a convenience, you make one of the most powerful lifestyle investments in your mental-health resilience.
References
- Blackwelder A, Hoskins M, Huber L. (2021) Effect of Inadequate Sleep on Frequent Mental Distress. Prev Chronic Dis ;18:200573. DOI: http://dx.doi.org/10.5888/pcd18.200573
- Conklin A., Yao C., Richardson C., (2018) Chronic sleep deprivation and gender-specific risk of depression in adolescents: a prospective population-based study. BMC Public Health. 18(1):724. DOI: https://doi.org/10.1186/s12889-018-5656-6.
- Gunderson J., McDaniel K., DiBlanda A. (2023) Association Between Insufficient Sleep, Depressive Symptoms, and Suicidality Among Florida High School Students . Prev Chronic Dis 2023;20:220403. DOI: http://dx.doi.org/10.5888/pcd20.220403
- Young VM, Bernal R, Baril A-A, et al. (2025) Long sleep duration, cognitive performance, and the moderating role of depression: A cross-sectional analysis in the Framingham Heart Study. Alzheimer’s Dement. 21:e70160. https://doi.org/10.1002/alz.70160
- Shah, A. S., Pant, M. R., et al. (2025). Effects of Sleep Deprivation on Physical and Mental Health Outcomes: An Umbrella Review. Am Jour of Lifestyle Med, 15598276251346752. https://doi.org/10.1177/15598276251346752
- Paruthi S., Brooks J., et al. (2016). Consensus Statement of the American Academy of Sleep Medicine on the Recommended Amount of Sleep for Healthy Children: Methodology and Discussion. Journal of clinical sleep medicine 12(11), 1549–1561. https://doi.org/10.5664/jcsm.6288
- Grace-Abraham N., Tran N., Moore C., & Jaqua E. (2025). Sleep in Adults: Normal Sleep and Its Importance to Health. FP essentials, 556, 6–11. Effect of Inadequate Sleep on Frequent Mental Distress.
- Patel A., Reddy V., Shumway K., et al. (2025) Physiology, Sleep Stages. [Updated 2024 Jan 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; Available from: https://www.ncbi.nlm.nih.gov/books/NBK526132/
- National Institute of Neurological Disorders and Stroke. (n.d.). Brain basics: Understanding sleep. Retrieved June 7, 2017, from https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-Sleep
