You're slumbering peacefully when your alarm goes off. Drat! You've forgotten to silence it on your day off. Speaking of which, there are no meetings, kids' chauffeur duties, or class lectures to drag you out of bed. In other words, there is no better excuse to sleep in, right?
Sleeping in on your rest days to catch up on zzz's lost due to work and other lifestyle demands is something many of us can relate to. In fact, roughly 56% of Americans “sleep less during the work week compared to non-work days.” Then, there are those who sleep in not necessarily because of sleep loss but just for the enjoyment of it.
If you assume sleeping in is a clear-cut solution to paying down sleep debt (the amount of sleep you've owed your body over the past 14 days) for better energy during the day, you’re on the right track. That said, there are a few things to take note of so that a later wake-up time won’t interfere with your circadian rhythm (your internal body clock). In this article, we use the two laws of sleep (sleep debt and circadian rhythm) to show you how to get the most out of sleeping in. Because at the end of the day, what we really want is sufficient sleep and circadian alignment so you can feel and function better.
When ample research shows a close relationship between oversleeping and various negative health risks, such as a higher risk of heart disease and early death, people tend to view sleep-ins in a negative light. Yes, regularly oversleeping is a common symptom in sleep disorders, like hypersomnia and sleep apnea, amongst many other chronic illnesses. But more often than not sleeping in isn't a harbinger of ill health.
Nine out of 10 times, the urge to lie in bed long after your alarm has rung is probably an indication of excess sleep debt spurring your body to get the rest it needs. In fact, the scientific literature explains sleeping in cannot be definitively proclaimed as a health risk or factor without considering a person's overall health outlook.
If you aren’t struggling with any health concerns related to oversleeping, focus on consistently meeting your sleep need (the genetically determined amount of sleep your body requires). If you need to sleep in once in a while to minimize sleep debt, go for it. You will be doing yourself a favor as keeping sleep debt low will help you function and feel as best you can in the near term. And in the long run, consistently low sleep debt is a formidable defense against the host of chronic illnesses that come with sleep deprivation.
Note: If you’re sleeping in more often than not, it may point to an underlying medical condition. In such cases, consult a healthcare professional to rule out any health problems.
Using the two laws of sleep — the two-process model of sleep regulation established by sleep scientist Alexander Borbély — sleeping in is a viable way to pay down sleep debt.
A recent study in the Journal of Sleep Research found that:
This new study shows that sleeping in on your rest days to pay down sleep debt from the workweek can insulate you from the high mortality rate short sleepers face.
Before you start turning off your alarm for good on the weekends, there's just one caveat to take note of. While sleeping in can help fend off sleep debt, it can also mess up your circadian rhythm, mainly in the form of social jetlag.
Jumping from an early sleep schedule during the workweek to a late one on your days off means that your internal clock has trouble keeping up with the dramatically fluctuating sleep patterns. This mismatch between your biological and social clocks, what's known as social jetlag, is a common form of circadian misalignment many of us struggle with.
The aftermath of social jetlag makes itself known through:
Circadian misalignment ultimately downgrades your daytime functioning abilities and aggravates sleep deprivation, frustrating the sleep debt-lowering benefit of sleeping in. What's more, scientific evidence shows that cortisol (an alertness-boosting hormone) typically peaks in the morning before declining rapidly throughout the day. Waking later than usual means you're working with less alertness and more sleepiness, so you aren't feeling and functioning at your best. Over time, circadian misalignment also intensifies your risk of specific health problems such as weight gain and obesity.
If you’re worried that you’re oversleeping when it comes to sleeping in, it’s likely an unfounded concern, as mentioned earlier. Instead, you’re probably waking up later in an effort to compensate for a high sleep debt.
Science explains your body has natural mechanisms in place to compensate for short sleep, most notably, the REM rebound effect. Basically, the frequency, depth, and intensity of REM sleep increases the next night after the previous night of insufficient sleep. A rise in non-REM sleep is also observed in short periods of sleep loss not exceeding six hours.
Due to the prolonged time spent in certain sleep stages, it’s no wonder you’re waking up later than usual. If you still need more convincing that sleeping in may not be due to ill health, take note that most of the studies on the subject speak to a correlation rather than causation. In other words, oversleeping is often a symptom or correlate of other health conditions, not their cause.
One caveat that you may be temporarily oversleeping is in relation to seasonal affective disorder (SAD). It’s a type of depression that occurs seasonally, particularly during winter when the nights are long and the days are short. The Journal of Psychosomatic Research discovered that 80% of people with SAD suffer from hypersomnia (excessive daytime sleepiness or extended nighttime sleep). Nearly 50% of the surveyed participants reported that they slept up to an additional two hours per day during winter. This oversleeping trend reverses back to normal when summer arrives or when participants undergo bright light therapy.
If you still aren’t sure whether the urge to sleep in is due to prior sleep loss rather than an underlying health condition, the RISE app can help to shed some light on that. RISE tracks your sleep debt relative to your personal sleep need. It uses sleep-science-based models and the past 365 nights of sleep data in your phone to calculate your sleep need in hours and minutes.
You can easily reference your current sleep debt on the Sleep tab in the app. As a rule of thumb, sleep debt that’s more than five hours is a likely indication for sleeping in. Once you have a clear idea of how much sleep debt you are carrying, you can avoid mistaking your desire to sleep in as a sign of impending emotional or physical ailment. At Rise, we are advocates of sleeping in for cutting down sleep debt. So, if you find yourself not meeting your sleep need, and you have the option to wake up later, go for it.
However, to avoid triggering circadian misalignment, try to only sleep in up to an hour past your usual wake time. RISE can help you with that, too. The app shows your ideal wake zone on the Energy Screen to give you an idea of how late you can schedule your next-day sleep-in.
That being said, if you’re extremely sleep-deprived, sleeping in for an extra hour may not sufficiently bring down your sleep debt. If that’s the case, explore other avenues of reducing sleep debt (see next section).
Sometimes, sleeping in may not be enough if your sleep debt is particularly large to begin with. To fully pay down your sleep debt, supplement your one-hour sleep-in with an afternoon nap and earlier bedtimes over a few consecutive nights:
As you can see, naps and an early bedtime (over consecutive nights) are added precautions should you have any leftover sleep debt after sleeping in. These three sleep debt-reducing practices work in tandem to help you catch up on sleep without throwing your circadian rhythm off balance.
If you still find yourself struggling with reduced daytime energy levels and increased nighttime sleep problems, focus on improving your sleep hygiene. (Our Sleep Guide shows you the steps to achieving good sleep hygiene.)
If you’re sleeping in to stock up sleep in anticipation of getting less sleep the next night, we’re here to tell you that it doesn’t work like that. Although sleeping in can help pay back sleep debt, oversleeping to “bank” sleep is actually a myth. We will use sleep homeostasis (the process that balances your biological urges for sleep and wakefulness) to explain why shoring up sleep isn't physiologically possible.
During wakefulness, a drowsiness-inducing compound called adenosine builds up, correlating to rising sleep pressure. When night falls, the burgeoning sleep pressure pushes you over the edge into slumber. As you sleep, your brain clears out adenosine to reset the sleep homeostat to zero come morning.
In the event of short sleep (you aren't meeting your sleep need), your brain doesn't have enough time to completely purge adenosine. Napping, sleeping earlier that night, and sleeping in the next day can help siphon off the remaining adenosine to relieve sleep pressure and return the sleep homeostat to zero once more.
When you're fully caught up on your sleep need (your brain has cleared away all the adenosine), the sleep pressure balance is already at zero. Sleeping in the next morning won't shift the sleep homeostat into a deficit to "hoard" sleep in advance.
When used correctly, sleeping in can help lower your sleep debt. As long as your sleep-in doesn't exceed an hour later than your normal wake time, you will likely feel more refreshed upon waking without incurring circadian misalignment.
If the extra hour of sleeping in doesn’t make a significant dent in your sleep debt, consider supplementing it with afternoon naps and earlier bedtimes. But you should keep in mind that the best way to keep your sleep debt low is to refine your sleep hygiene and consistently meet your sleep need.
For those whose sleep hygiene is already pretty good, and want to sleep in due to an occasional late night, RISE can help you plan ahead. The app shows your ideal wake zone on the Energy screen so you have a clear idea of how late you can get away with sleeping in.
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