The quality of sleep is closely linked to its continuity. Waking up frequently during the night disrupts the functional structures of sleep cycles. Achieving better sleep requires that the brain can progress through the various sleep stages seamlessly.

“Good sleep isn’t just luck. Good sleep is like good food: when we have great ingredients and know what to do with them, the magic can happen.”

Have you ever fallen asleep without much trouble, and then found yourself waking up several times during the night? Or perhaps you slept for what seemed like enough hours, but in the morning, you still didn’t feel properly rested.
One important factor that may help explain these experiences is sleep continuity — how well our nervous system can move through the many sleep stages throughout the night, with minimal disruption.

As we discussed in the previous newsletter, getting enough sleep is important, but so is the quality of those hours. Our sleep naturally moves through different stages, from lighter sleep to deeper NREM sleep and REM sleep. These stages serve different functions, and the brain needs opportunities to move through them repeatedly during the night.

Brief awakenings and changes in sleep stages are normal. However, sometimes awakenings can disrupt this natural progression and leave us feeling less refreshed in the morning. So, what could helps us promote optimal sleep continuity?

One way to understand sleep is to look at the ongoing communication between the brain and the body. Neuroscientist Lisa Feldman Barrett, in her work on the brain and constructed emotion, emphasizes the importance of allostasis: the brain's ongoing regulation of the body's energy needs and internal resources.

This regulation doesn't stop when we fall asleep. Throughout the night, the brain continues to monitor the body's internal condition and coordinate the processes needed to maintain a stable internal environment.

But here's what makes this particularly interesting: the relationship between the brain and body works in both directions. The brain regulates bodily functions, including breathing, heart rate, digestion, and temperature regulation. At the same time, information from the body travels back to the brain, influencing how it responds to the body's changing needs

This ongoing exchange shapes our internal state. And it has an important implication for sleep: the state of your body influences how readily your brain settles into sleep and moves smoothly through its stages.

One of the key communication pathways between the body and brain is the vagus nerve. The vagus nerve carries sensory information from organs such as the heart, lungs, and digestive tract to the brain. It also carries signals that help regulate bodily functions, including heart rate and digestion.

As part of the parasympathetic nervous system, it plays an important role in supporting rest and recovery. When we’re under pressure, worried, or dealing with prolonged stress, our nervous system may remain more alert than the situation requires. We may notice this in our breathing, muscle tension, heart rate, or general sense of unease.

If we carry that state into the evening, settling down may become more difficult. This doesn’t mean that stress automatically causes disrupted sleep, or that a particular level of vagal activity guarantees an uninterrupted night. Sleep is influenced by many interacting factors. However, learning to regulate our nervous system can be a valuable way to prepare for sleep, and to support its continuity through the night. By gently influencing our breathing, muscle tension, and awareness of bodily sensations, we can help the body shift toward a calmer state before bedtime.

Slow, comfortable breathing, gentle movements, and targeted relaxation are all ways to explore this process. Rather than forcing the body to relax, we give the nervous system different sensory experiences and an opportunity to respond to them.

Over time, this can help us become more familiar with the sensations associated with calmness and relaxation. And that is where mindful movement, and somatic practice can play a role in preparing for sleep.

Nervous-system regulation is an important part of the picture, but it doesn’t work in isolation. Several other bodily processes can influence how continuously we sleep.

Body temperature
Our core body temperature naturally declines as part of the process of preparing for sleep. A bedroom that is too warm or too cold can interfere with comfortable, continuous sleep.

Metabolic stability
The body continues to regulate its energy supply during the night. For most healthy people, these processes maintain blood glucose within an appropriate range. However, certain medical conditions and medications can contribute to nighttime awakenings. If you suspect this applies to you, it’s worth discussing with your doctor.

Stress and inflammation
Stress, illness, pain, and inflammation can influence sleep through several pathways. When the body is dealing with discomfort or an ongoing challenge, sleep may become lighter or more fragmented.

The gut-brain connection
Communication between the digestive system and the brain also plays a role in regulating the body’s internal state. The gut microbiome is an area of active research in sleep science, although the precise role of microbiome-related signals in maintaining continuous sleep is still being investigated.

These factors remind us that sleep is part of a larger system in which the brain and body continuously respond to one another.

So, what can we take from all this? First, we need enough time for sleep. Second, we need to consider what might be interfering with its continuity. And third, we can learn to pay attention to the state of our nervous system before bed.

Instead of treating bedtime as a sudden switch from activity to sleep, we can see it as a transition. How does your breathing feel after a demanding day? Can you sense unnecessary tension in your face, jaw, shoulders, or back? Do you feel settled, or does your body still seem ready for action?

You don’t need to analyze every sensation. Simply noticing is a useful starting point. From there, gentle movements and breathing variations can offer new sensory information and help you explore different ways of being at ease. Sleep continuity is not something we can force, but by developing a better understanding of our body-brain system, we can create more favorable conditions for it.

And this brings us back to the central idea of this series: exceptional sleep is not simply about the number of hours we spend in bed. It is about giving the brain and body the time, conditions, and opportunity to carry out the processes that make sleep restorative.

The aim of this exercise is to improve the flow of calming sensory information from your hands to your brain and to improve awareness of the possibility of using hands to support nervous system regulation.

Exercise

One benefit of quality sleep is that it helps regulate your body's hormonal system, including cortisol, often called the primary stress hormone. Cortisol plays several important roles, from helping your body respond to stress and mobilize energy to regulating immune activity. How this works is that cortisol follows a natural daily rhythm, typically rising toward the morning to help prepare you for the day and falling toward the evening. Insufficient or disrupted sleep can interfere with this rhythm and alter cortisol levels. When these changes persist, they may contribute to difficulties with stress regulation and affect your overall health. In other words, quality sleep does more than help you feel rested. It also gives your body an important opportunity to maintain the hormonal rhythms that support healthy functioning. That's another reason to make quality sleep a daily priority.

The state of your body shapes how easily your brain settles into sleep and moves through its stages.

Before bed, treat the evening as a transition rather than a switch. Take a few minutes to check in with your body: How does your breathing feel? Is there tension in your jaw, shoulders, or back? Then try this week’s somatic practice, slowly exploring your left hand with your right, to give your nervous system a calm, sensory signal that it’s safe to settle. Notice what changes, without trying to force relaxation.

Thanks for reading!

Until next week, wishing you restful nights and brighter days.

Oliver

Next week: What is Light Sleep and Why It Matters.

New to Leveling Up Sleep?
Start from the beginning: Welcome to Leveling Up Sleep
Previous week: The Right Amount of Sleep

P.S. Have a question about sleep? What's your biggest sleep challenge, or what would you like me to cover in a future issue? Simply reply to this email. There's a good chance your question will be answered in a future issue.