There are two internal systems that drive our ability to sleep, to maintain sleep, and fall asleep when we want to fall asleep.
1. Homeostatic Sleep Drive
The first one is what we call the homeostatic drive. And that’s a pretty simple one. It just says the longer I’m awake, the more tired I’m going to be. So time and intensity here. So the longer I’m awake, the more tired I’m going to get and it’s continually driving that I want to fall asleep. So in some of the treatment we do around Cognitive Behavioral Therapy for Insomnia (CBTI) is we want you to be sleepy and tired and fatigued when you fall asleep. So one of the things we actually do in this process, we restrict time in bed. A lot of people who develop insomnia say I need to spend more time in bed to get the same amount of sleep because I wake up a lot or it takes me a lot longer to fall asleep or I wake up too early, so they start spending more time in bed.
And that actually decreases the drive to sleep. So they find their sleep becoming more fragmented over time. They find themselves having longer times to fall asleep or they wake up too early. So one of the things we’re going to do is we’re going to restrict time in bed so we can develop this strong drive to sleep. The longer you’re awake, the more fatigued and tired you’re going to be and the more your sleep is going to be consolidated. So that’s the homeostatic drive.
2. Circadian Rhythm: Your Biological Sleep Clock
The other drive that allows us to fall asleep and maintain sleep is the circadian rhythm. And what we noticed is that we become very sleepy and tired and then we seem like we’re kind of wide awake and then we become sleepy and tired again as the night goes along. So this circadian drive is bi-phasic and what we do.
So one of the things that’ll happen with that is if you start changing the times that you fall asleep or start changing the times that you wake up in the morning, what that does, it sets you into what we call this eternal kind of jet lag. And if you’ve ever noticed that when you traveled overseas or travel over multiple time zones, it seems like when you should be asleep, you’re awake and when you should be awake, you kind of feel sleepy. That’s because we’ve had this shift in our circadian rhythm and the time we should be falling asleep, maintaining sleep. So one of the things we do with Cognitive Behavioral Therapy is we want to maintain consistent wake time, consistent bedtime night after night after night. We need consistency because our circadian rhythm demands that. So we want consistency over time. We want this drive to sleep over time. So we’re going to take away napping. We’re going to require you to fall asleep and maintain sleep at the exact same times every night, and you’ll find yourself over time, and it takes a little bit of time to do it, within a week or two, you’re going to find yourself consolidating your sleep because you are going to be ready to go to sleep and your circadian rhythm is going to be in sync and ready for you to fall asleep.