Rethinking Sleep: Fresh Answers to Your Biggest Sleep Questions

In our last post at Affectable Sleep, we challenged the idea that 8 hours of sleep is the universal key to better health, sparking questions about what truly makes sleep restorative. This follow-up dives into some of the most common sleep struggles we hear about and aims to clear up confusion around the 8-hour rule, and showing why quality, not just quantity, drives sleep’s power to heal and refresh us.

I’ve been sleep deprived for a while—how much long-term damage did I do?

We’ve all had the odd sleepless night, whether it’s work related or a big night out, that’s part of living a full life. But extended sleep deprivation risks lasting harm. The glymphatic system acts like the brain’s waste removal service, clearing metabolic waste such as amyloid-beta during deep sleep. This process relies on slow-wave sleep, when cerebrospinal fluid flushes through the brain, removing toxins that build up while you’re awake. When your body lacks quality sleep, this clearance weakens, leaving waste behind. A study found that disrupting deep sleep in healthy adults increased amyloid-beta levels in cerebrospinal fluid by about 10 percent in a single night [1]. It might be fine if one bad night was the end of it, but the problem compounds. It is theorized that increased amyloid-beta further impairs the glymphatic flush, meaning the brain struggles even more to clear waste on following nights. It’s a vicious cycle that may take years to manifest, potentially contributing to Alzheimer’s risk, as noted in research showing that higher amyloid levels predict cognitive decline in healthy adults over 3 years [2].

I’ve been focusing on the effects of sleep deprivation, but in the study I mentioned above, the damage to the glymphatic system and buildup of metabolic waste didn’t come from sleep deprivation in the traditional sense. Researchers hindered deep sleep without altering total sleep time, showing that poor sleep quality, even with enough hours, can have effects similar to sleep deprivation [1]. This matters because damage isn’t just from missing sleep—it’s about not getting the necessary restorative brain function, irrespective of time.

Research has shown that using acoustic stimulation during slow-wave sleep can improve memory performance and produce a beneficial amyloid response in older adults [3]. These improvements in memory lasted beyond the stimulation period, suggesting that enhancing slow-wave activity may help break the cycle between poor sleep and brain health decline. This shows how our understanding of the brain is evolving and how processes like slow-wave enhancement can support the brain’s restorative function during sleep.

Does this mean there are no consequences to extended sleep deprivation? No. That’s like saying obesity doesn’t matter because we can take Ozempic later to fix it. We now have tools to optimize our brain’s restorative function, but they don’t replace our duty to care for our health with consistent quality sleep.

References:
[1] Ju, Y. E., et al. (2017). Slow wave sleep disruption increases cerebrospinal fluid amyloid-β levels. Brain. DOI: 10.1093/brain/awx148.
[2] Donohue, M. C., et al. (2017). Association Between Elevated Brain Amyloid and Subsequent Cognitive Decline Among Cognitively Normal Persons. JAMA. DOI: 10.1001/jama.2017.6669.
[3] Wunderlin, M., et al. (2023). Acoustic stimulation during sleep predicts long-lasting increases in memory performance and beneficial amyloid response in older adults. Age and Ageing. DOI: 10.1093/ageing/afad228.

‍

‍

I regularly feel tired, even after 8 hours of sleep, but I don’t know why.

You’ve been told that 8 hours of sleep should leave you refreshed, so why are you still dragging through your day? When I talk to people about this, one issue often stands out: an irregular sleep schedule. Your body craves consistency, and erratic bedtimes can disrupt the natural rhythm of your sleep cycles, leaving you unrested even after a full night of sleep.

When I first heard about sleep hygiene, I thought it was nonsense. Why would a consistent bedtime change how my body slept? But then I started comparing it to our daily diet and eating schedule, and it clicked. If you eat lunch at noon every day and suddenly skip it, your body notices—you feel hungry because it expects food at that time. Sleep works the same way. A regular bedtime trains your body to lower cortisol, the stress hormone that keeps you alert, and increase adenosine, a chemical that signals it’s time to rest. An inconsistent schedule throws this off. Your body doesn’t know what hormones to ramp up or reduce when because you’re causing it to guess when you might be going to sleep. Erratic sleep timing doesn’t just impact your ability to fall asleep, it alter slow-wave sleep effectiveness, even if you get a full 8 hours[5]!

Feeling tired after 8 hours often means your brain and body are achieving the restorative processes necessary for optimal health. It’s a signal of what your body needs. Enhancing slow-wave activity can help, ensuring the sleep you get is as effective as possible. Slow-wave enhancement has been shown to improved heart rate variability, a marker of autonomic balance and overall health[6].

But what if you have an erratic schedule? If you’re a shift worker, for example, maintaining a consistent bedtime can feel impossible. Research has pointed to wake time being more important than total sleep hours when measuring subjective tiredness and cognitive function, like attention and memory [7]. This further shows that it’s not just about how long you sleep, but the cyclical patterns and restorative function that are vital for feeling refreshed.

References:
[5] Van Der Werf, Y. D., et al. (2017). The impact of irregular head-start times on weekly rhythms of slow-wave and REM sleep. Scientific Reports. DOI: 10.1038/s41598-017-03171-4.
[6] Diep, C., et al. (2021). Acoustic enhancement of slow wave sleep on consecutive nights improves autonomic functioning measured via heart rate variability. Journal of Sleep Research. DOI: 10.1111/jsr.13289.
[7] Kim, J. K., et al. (2020). Quantifying Cognitive Impairment After Sleep Deprivation at Different Times of Day: A Proof of Concept Using Ultra-Short Smartphone-Based Tests. Sleep Medicine Reports. DOI: 10.1016/j.sleepx.2020.100025.

‍

‍

How long after having my child will it take to recover my sleep?

New mothers often wonder when sleep will feel restorative and rejuvenating again. The demands of motherhood, like frequent night wakings and the stress of caring for a young child, can fragment sleep for years. Research shows that poor sleep quality in new mothers is linked to higher stress levels, a pattern that can persist well beyond the early postpartum months [8].  

This challenge is amplified because women are having children later in life, often in their 30s or 40s. When women had children in their 20s, there was a window to recover from poor sleep and return to feeling rested, but now, the post-early childhood sleep struggles overlap with the natural age-related decline in sleep quality [9]. This is further exacerbated by perimenopause and menopause, which often start in the 40s, now just a few years postpartum, robbing todays mother of the historically available decade of recovery time.

Fragmented sleep and ongoing stress mean your brain and body struggle to achieve the restorative processes necessary for optimal health. Slow-wave sleep, the foundation of health, is key for recovery, but these disruptions make it harder to access. Research shows that enhancing slow-wave activity can help, reducing early-night cortisol and, improving immune function, which supports deeper, more restorative sleep [10]. This approach can enhance recovery even for those with limited sleep opportunities or fragmented sleep, like new mothers, by improving the restorative function of the sleep they do get [11].

References:

[8] Härdelin, G., et al. (2021). Do Mothers Have Worse Sleep Than Fathers? Sleep Imbalance, Parental Stress, and Relationship Satisfaction in Working Parents. Nature and Science of Sleep. DOI: 10.2147/NSS.S312149.
[9] Ohayon, M. M., et al. (2004). Meta-Analysis of Quantitative Sleep Parameters From Childhood to Old Age in Healthy Individuals: Developing Normative Sleep Values Across the Human Lifespan. Sleep. DOI: 10.1093/sleep/27.7.1255.
[10] Besedovsky, L, et al. (2017).Auditory closed-loop stimulation of EEG slow oscillations strengthens sleep and signs of its immune-supportive function. DOI: 10.1038/s41467-017-02170-3.
[11]Diep C., et al. (2021). Acoustic enhancement of slow wave sleep on consecutive nights improves alertness and attention in chronically short sleepers Sleep. DOI: 10.1093/sleep/zsab123.

‍