Sleep Pressure Simplified: Methods and Mechanisms
Two simple, but powerful, strategies for healthy sleep.
I went on an evening group run for the first time in a long time. It was nice to spend time with others who value fitness. But I found myself constantly checking my watch. While I was running, I was simply ready to head back home and start winding down my day.I didn’t get home until 9 PM and fell asleep around 11 PM or so, which, for me, is late. Fortunately, my sleep normalized over the next few days, but not without effort.
There are two things I want to be clear about here. First, social support is helpful for sleep, but social jet lag, delaying sleep because of social responsibilities and engagements, is not. We should prioritize a regular wind down time and sleep interval. Second, beliefs we hold about sleep contribute to our sleep health. Feelings of anxiety and worry before sleep (i.e., pre-sleep arousal) can reduce our ability to feel calm enough to fall asleep and stay asleep throughout the night. Part of my issue with getting to sleep after the evening run may have been related to my worry about having enough time to wind down when I got home for my typical bedtime (e.g., 9:45 PM). Now, let’s talk about why it helps to maintain a consistent sleep schedule.
Start with sleep consistency — the ideal.
The ideal sleep goal is to maintain a consistent sleep schedule, getting ready for bed around the same time each night and waking up around the same time each morning. Regular sleep is arguably one of the most important components of sleep health because it supports healthy sleep duration and sleep efficiency. For example, using mattress-based bed sensors, a recent study showed higher sleep efficiency and lower sleep latency (i.e., time to fall asleep) in a sample of over 300,000 participants.
With high sleep regularity, the body has a predictable rhythm for the time to sleep and the time to wake up (i.e., circadian rhythm). Throughout our wake periods, we build sleep pressure. In other words, as the day progresses, we gradually start to feel sleepy. This is called Process S, our homeostatic sleep drive. We are also sensitive to clock time and changes in light exposure. When our environments are darker and night falls, we start to feel sleepy; this is called Process C. Adhering to our natural rhythms regarding when we feel sleepy and when we feel alert helps us to maintain healthy sleep, that which is consistent, efficient, and of sufficient duration.
The problem many of us have with sleep consistency is that our lives are dynamic. Circumstances change, timing gets in the way, and we sometimes have to adapt to the schedules of others. Though we should aspire to maintaining consistent wind down times, we cannot get to sleep within the same time interval every night. The goal is idealistic and unrealistic for the majority of us. But, we can still sleep well in spite of this. And, in a way, because of it. We just have to get ourselves back on track by manipulating a simple process: sleep drive.
Maintain sleep drive — the failsafe.
Some nights just don’t go as planned. We stay out a little too late; we have a family emergency; or work runs later than normal. These things happen. They aren’t usually our fault, but they challenge our abilities to get to sleep and to sleep well. There’s still hope for improving our sleep after these sorts of challenges Even after nights of poor sleep, we can look forward to better sleep ahead.
Sleep drive builds over time. Aric Prather’s book, The Sleep Prescription , helped me understand different perspectives on poor sleep. My favorite illustration from the book is to imagine sleep pressure as a balloon. The longer we are awake, the more pressure is entered into the balloon, and if we allow the pressure to build, we may fall asleep more easily during the next sleep period. The trick is to avoid relieving the pressure until time for the next typical sleep interval.
But we must first consider some caveats. Sleep deprivation is dangerous. We should not try to function as we would after nights of particularly short sleep (e.g., 5 hours or less). After undergoing sleep deprivation or sleep restriction, people are often at risk of making mistakes similar to the kinds of mistakes people make after alcohol intoxication. Thus, we should behave cautiously, and ideally, avoid anything we would avoid if intoxicated, including work responsibilities, making important decisions, and driving or operating any vehicle.
Provided such cognitively demanding activities can be set aside for the day, we can safely maintain our sleep pressure without making a conscious effort to relieve it (e.g., with caffeine or long naps) until our next sleep interval. This way, we are able to reset, getting ready for bed at around the same time and waking up at around the same time each day.
While resetting our sleep schedules by playing with sleep drive may help, it is only a failsafe method. Ideally, we want to maintain sleep consistency and for that, we need to set boundaries.
Take on the real challenge — set (time) boundaries.
Setting boundaries is something I’ve struggled with in the past. While I’ve gotten better with delimiting time I need for myself, my social relationships, and my work, it is still a challenge. One way I've set boundaries involves using a combination of analog and digital note-taking, journaling, and time blocking.
A key strategy that has helped me set boundaries is changing the way I think about my time. While I may agree to some activities and responsibilities that I don’t love, I limit my engagement with them. For most activities, I time block. I set hard stops. I plan my time off, time to myself, time with others, and of primary relevance here, my time to sleep.
I encourage you to challenge the way you think about time and reflect on how it impacts your sleep health. How do we balance social engagements, professional responsibilities, and time for ourselves, including time for sleep? What are your strategies?
Notes
If you are consistently having trouble with your sleep, I recommend consulting a trusted medical professional.
For a comprehensive sleep guide, read Aric Prather’s book, The Sleep Prescription: Seven Days to Unlocking Your Best Rest.
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