Don't Sleep Too Long

??In this Nexus:

?? Stages of sleep

?? The link between sleep and longevity

?? Don't sleep too long - the optimal length of sleep

?? How you can improve your sleep quality?

Sleep is one of the core elements, which made me become so interested in the field of longevity. I have already mentioned in the first edition of Nexus how poorly I was sleeping for quite a long period of time (for over 5 years). I even have a name for the sleepless nights dedicated to work. I call it the Cyborg Mode. This means that you work until 2-3 AM in the morning and then you try to be functioning normally the next day. This is of course supported by the enormous amount of coffee to keep the "wheels turning". 3-4 double espressos was the usual.

I think I am now suffering the consequences of such a "sleep routine" in the past. It takes me quite a long time to fall asleep (usually around 30 minutes or even longer). From time to time I wake up in the middle of the night (at 4-5 AM) and can't fall asleep for an hour or two. Therefore, any methods to improve the quality of sleep is in the centre of attention for me. In this Nexus I will discuss the stages of sleep, the link between sleep and longevity, what is considered to be the optimal sleep duration and the methods to improve your sleep quality.

Stages of Sleep

Sleep is categorised into two main types: non-rapid eye movement (NREM) sleep, which includes three stages (N1, N2, N3), and rapid eye movement (REM) sleep. We better know it as the light sleep (stages N1 and N2), deep sleep (stage N3) and REM sleep, as shown in the picture below (1 ). These are the usual stages of sleep in all of our smart devices.

Non-REM Sleep

Stage 1 (N1). This is the lightest stage of sleep, often considered the transition phase between wakefulness and sleep. It is characterized by slow eye movements, reduced muscle activity, and the ability to be easily awakened. It lasts for about 1-7 minutes. This short duration is optimal, as a longer duration might indicate difficulty entering deeper sleep stages.

Stage 2 (N2). In this stage, eye movements stop, heart rates slow, and body temperature decreases. It acts as a buffer to deeper sleep stages. This stage last for about 10 to 25 minutes during the sleep cycle in adults. It's crucial for memory consolidation and physical recovery.

Stage 3 (N3), Deep Sleep. This is the deepest stage of NREM sleep, which is characterised by slow breathing, decreased heart rate, and relaxed muscles. This stage is critical for physical recovery, immune system strengthening, and growth hormone release. It should take 20-40 minutes of the sleep cycle. During this stage the body repairs and regenerates tissues, builds bone and muscle, and strengthens the immune system.

REM Sleep

REM Sleep. REM sleep is marked by rapid eye movements, increased brain activity, and vivid dreams. It's crucial for processing emotions, consolidating memories, and learning. During REM, the body becomes temporarily paralyzed, preventing us from acting out our dreams. REM stage takes between 10 to 60 min of the sleep cycle. The first REM cycle of the night might last only a short time, but with each cycle it gets longer, culminating in the longest REM period just before awakening as shown in the visual below (1 ).

Why it is important to understand the stages and cycles of sleep? Because only then you can identify if you are sleeping well and if you need to change anything in your sleep patterns. I check my sleep score every morning on my smart watch and try to link the abnormalities or low sleep scores with what I did wrong a day before. Over time it improves my self-awareness and helps me maintain a better sleep routine.

What Does Science Say?

The Link Between Sleep and Longevity

Under normal circumstances, people spend about a third of their lives sleeping or trying to sleep. This sleeping time is incredibly important because it allows our bodies to recover and recharge, which is essential for our health, happiness, longevity, and how well we function during the day. This shows us that getting enough good-quality sleep is crucial for maintaining our daily routines. Having a regular sleep schedule is not just about feeling rested, it is a key part of staying healthy and meeting our body's basic needs every day.

Scientific evidence increasingly supports a vital role of sleep in longevity. Insufficient sleep may contribute to chronic diseases, such as obesity (2 ), cardiovascular disease (3 ), and diabetes (4 ). Lack of sleep may also lead to depression (5 ), other mood disorders, and reductions in cognitive performance, including memory and learning difficulties (6 ). This shows that sleep affects numerous physiological processes, including metabolic regulation, immune function, and cognitive health, which collectively influence the aging process.

• Metabolic Regulation. Adequate sleep is crucial for maintaining metabolic homeostasis. Sleep deprivation disrupts glucose metabolism and increases the risk of obesity and diabetes, conditions associated with shorter lifespan and healthspan. Sleep deficiency can result from several sleep and circadian disorders including insufficient sleep, insomnia and narcolepsy (a sleep disorder that makes people very drowsy during the day). Shift work can induce circadian misalignment contributing to sleep deficiency. There is a relationship between obesity and sleep apnea (a disorder in which a person frequently stops breathing during sleep) and apnea results in both hypoxemia (low level of oxygen in the blood) and sleep deficiency. Sleep deficiency is also associated with increased risk of obesity. Sleep deficiency, circadian misalignment, obesity and hypoxia are associated with increased inflammation, oxidative stress, impaired glucose tolerance and insulin resistance. Thus, sleep problems likely increase type 2 diabetes risk through multiple pathways (7 ).

• Immune Function. Sleep enhances immune defense, promoting the production of cytokines (agents that modulate or alter the immune system response) and facilitating the elimination of pathogens. Chronic sleep deprivation weakens the immune response, increasing susceptibility to infectious diseases and potentially accelerating aging. Sleep is crucial for consolidating memory in the brain and strengthening the immune system. Memory processes, both in the brain and immune system, involve three phases. Encoding, where information or pathogens are first encountered. Consolidation, where this information is stabilized and stored long-term, with brain memories moving between regions and immune memories transferring from antigen-presenting cells (a type of immune cell that boosts immune responses by showing antigens on its surface to other cells of the immune system) to T cells (a type of white blood cells which are part of the immune system). Recall, where memories are accessed or, in the immune system, where memory T and B cells (or B lymphocyte, a key player of the adaptive immune response) are activated. Slow-wave sleep (N3), in particular, plays a significant role in the consolidation phase for both memory types (immune and cognitive memory) (8 ).

• Cognitive Health. Sleep is essential for cognitive function, including memory consolidation, learning, and emotional regulation. Long-term sleep deprivation is linked to the development of neurodegenerative diseases like Alzheimer's (9 ), which shortens life expectancy and strongly affects the quality of life. As explained before, sleep not only affects our immune system memory, but the brain memory as well.

Don't Sleep Too Long - the Optimal Length of Sleep

The optimal sleep duration varies across the lifespan, with adults generally requiring somewhere between 6 to 8 hours per night for optimal health benefits. A systematic review and a dose-response meta-analysis of prospective cohort studies aimed to quantify the dose-response relationships of sleep duration with risk of all-cause mortality. For all-cause mortality, when sleep duration was less than 7 hours per day, the pooled relative risk (RR) was 1.06 (95% CI, 1.04–1.07) per 1-hour reduction. When sleep duration was over 7 hours per day, the pooled RR was 1.13 (95% CI, 1.11–1.15) per 1-hour increment (10 ).

This means that if you sleep less than 7 hours, with every hour you steal from yourself, the all cause mortality increases by 6%. Interestingly, a longer sleep duration is even worse, as every hour in addition increases the all cause mortality by 13%. It is worth mentioning that the optimal sleep duration is quite individual, thus it is worth tracking your sleep quality daily and identifying what works best for you personally.

How You Can Improve Your Sleep Quality?

Improving sleep quality and achieving the optimal duration can significantly contribute to your healthspan and lifespan. As mentioned at the beginning of this Nexus , anything that says "improves your sleep quality" immediately grabs my attention. Here are several evidence-based strategies:

• Consistent Sleep Schedule. Maintaining a regular sleep-wake cycle helps synchronize the body's internal clock, improving sleep onset and quality. This is the hardest for me to follow, especially with loads of travel to different time zones. However, when I manage to go to bed and wake up at similar time for a longer period of time, it definitely improves my sleep quality and helps me fall asleep faster.
• Sleep Environment Optimization. Creating a comfortable sleep environment (cool, dark, and quiet) can significantly enhance sleep quality. Simple things as comfortable mattress and pillow, minimizing light and noise pollution are key steps in creating such a good sleep space. I have a blackout curtains in my bedroom (wouldn't survive without those) and I always try to leave the window open before I go to sleep to lower the temperature in the room as much as possible.
• Mindful Eating and Drinking. Avoid caffeine and heavy meals before bedtime to prevent sleep disturbances. The half-life of caffeine in the body is 3-6 hours, therefore, you should drink your last cup of coffee at least 4 hours before bed. While alcohol may seem to have a sedative effect, it can impair sleep quality in the latter half of the night, at its' half-life in the body is around 5 hours. Therefore, you should follow the rule of centenarians from the blue zones not to drink alcohol after 5PM (or around 5-6 hours before sleep).
• Physical Activity. Regular physical activity promotes faster sleep onset and deeper sleep. However, exercising too close to bedtime may have a stimulating effect, so the timing is crucial here. I see how my sleep quality is improving when I exercise regularly and I try to finish any intense physical activity at least 3 hours before bedtime for my cardiovascular system to calm down and prepare for sleep.
• Stress Management and Relaxation Techniques. Practices such as meditation, deep breathing, and progressive muscle relaxation can reduce stress and promote better sleep. While I do not meditate myself, I really noticed how deep breathing helps me fall asleep faster in cases when I struggle to do so.
• Limiting Screen Time. Exposure to blue light from screens can disrupt circadian rhythms. Limiting screen time in the evening can help maintain natural sleep patterns. Of course in the age of social media it is hard to do and you have to be mindful about stopping scrolling your phone or tablet at least 30 minutes before sleep.
• Food supplements. Of course, when nothing else works or in cases of the time-zone change, food supplements can help fall asleep faster. These include the best known melatonin, magnesium, valerian root, ashwagandha, etc. The first two are always near my bed and I have really noticed how it helps me improve my sleep quality. I try to use it only in cases when I feel that the sleep will not come easily.

The relationship between sleep and longevity highlights the importance of prioritizing sleep as a key component of a healthy lifestyle. By aiming for the optimal duration of sleep and adopting strategies to improve sleep quality, you can significantly enhance your healthspan. Hope you enjoyed the read. More on longevity and healthspan is coming in 2 weeks. Make sure to subscribe and share your thoughts!