Key Takeaways
- Deep sleep is essential for brain health, memory consolidation, and longevity, yet many adults don’t get enough of it.
- Your eating window, light exposure, stress levels, and sleep consistency all play major roles in deep sleep quality.
- Sleep changes as you age, but strategies like minimising blue light, optimising meal timing, and creating a wind-down routine can help improve deep sleep.
If you’ve ever woken up feeling exhausted despite getting a full eight hours of sleep, chances are you didn’t get enough deep sleep. Deep sleep, or slow-wave sleep (SWS), is the most restorative stage, essential for brain detoxification, muscle repair, and immune function.
Most deep sleep occurs early in your sleep cycle, typically within the first third of the night. If you miss this window, you lose out on its restorative effects (R). This is why sleep consistency and pre-bed routines are crucial for maximising deep sleep.
As you age, deep sleep naturally declines, with studies showing that by middle age, you may get only half the deep sleep you had in your twenties (R). However, certain lifestyle changes can help you regain and improve deep sleep quality.
How Ageing Affects Sleep
Sleep changes significantly as you age, and many people over 40 notice a decline in both sleep duration and quality.
- Reduced Deep Sleep – Studies show that deep sleep declines by 2% per decade after the age of 30 (R). Older adults often spend more time in lighter sleep stages and wake up more frequently during the night.
- Circadian Rhythm Shifts – Your body’s internal clock naturally shifts forward, making you tired earlier in the evening and wake up earlier in the morning (R).
- Increased Sleep Fragmentation – Light sleep increases with age, making it easier to wake up due to noise, temperature changes, or discomfort (R).
- Hormonal Changes – Melatonin levels gradually decline as you age, making it harder to fall and stay asleep (R).
- More Frequent Night Wakings – A higher risk of nocturia (night-time urination) disrupts sleep patterns (R).
- Chronic Pain and Sleep Disorders – Conditions such as arthritis, sleep apnoea, and restless leg syndrome become more common with age, further affecting deep sleep quality (R).
Although ageing naturally reduces deep sleep, optimising lifestyle, environment, and habits can counteract these changes and improve sleep quality.
Factors That Affect Deep Sleep
1. Eating Too Late Can Reduce Deep Sleep
Eating too close to bedtime raises body temperature and blood sugar, disrupting melatonin production and sleep cycles (R).
Best Practices:
- Avoid eating at least 2-3 hours before bed to allow digestion to finish.
- Experiment with longer fasting periods and observe how your deep sleep improves.
- If hungry at night, opt for a light, protein-rich snack like Greek yoghurt or nuts.
2. Irregular Sleep Schedules Reduce Deep Sleep
Your body thrives on routine. Going to bed at different times each night disrupts your circadian rhythm, making it harder to get deep sleep.
Best Practices:
- Choose a consistent bedtime and aim to be in bed within ±30 minutes every night.
- Set an alarm for bedtime, not just for waking up.
3. Exposure to Blue Light at Night Blocks Deep Sleep
Blue light from screens suppresses melatonin and delays sleep onset (R)
Best Practices:
- Turn off screens at least one hour before bed.
- Dim household lights or use amber/red light bulbs after sunset.
- Use blue-light-blocking glasses if screen exposure is unavoidable.
4. Caffeine and Alcohol Disrupt Deep Sleep
Caffeine and alcohol both impact deep sleep:
- Caffeine: Blocks adenosine, a sleep-promoting neurotransmitter, delaying deep sleep onset (R).
- Alcohol: Induces drowsiness but reduces time spent in deep sleep, leading to fragmented rest (R).
Best Practices:
- Avoid caffeine at least 6-12 hours before bed.
- Avoid alcohol if deep sleep is a priority—even one drink can reduce deep sleep (R).
- Opt for herbal teas like chamomile, valerian root, or passionflower.
How to Improve Your Deep Sleep Naturally
Develop a Wind-Down Routine to Prepare Your Body for Sleep
A structured wind-down routine can significantly improve deep sleep by lowering stress hormones and calming the nervous system.
Best Practices:
- Take a short evening walk to lower stress and regulate blood sugar.
- Engage in low-stimulation activities like reading, meditation, or breathwork.
- Avoid mentally stimulating activities or intense exercise close to bedtime.
Take Action for Better Sleep Tonight
If you’re not waking up feeling refreshed, it’s time to prioritise deep sleep. Start by:
✔ Finishing dinner at least 2-3 hours before bed.
✔ Sticking to a consistent bedtime (within ±30 minutes every night).
✔ Eliminating blue light exposure one hour before bed.
✔ Avoiding caffeine and alcohol before bedtime.
✔ Creating a wind-down routine with relaxing activities.
Deep sleep is a superpower for longevity—optimising it will enhance your brain function, immunity, and overall well-being.
Want to learn more about optimising your health for longevity? Read our blog on How Does Sleep Improve Longevity?
