If you savor the luxury of sleeping in for hours on the weekend, you're not alone. About one-third of American adults don't get enough sleep, and many try to make up for it on their days off work or school. Although sleeping in is often seen as a quick-fix for catching up on rest, it may actually have the opposite effect. Sleeping in can make you even more tired because it affects your circadian rhythms.
If you feel the need to sleep in on your days off, you might not be getting enough sleep overall, according to the National Heart, Lung and Blood Institute. Adults between the ages of 18 and 60 should be getting at least seven hours of sleep a night for optimal rest and health benefits.
When you don't reach this threshold, you fall into what researchers call a sleep debt. An adult who gets five hours of sleep a night instead of the recommended seven hours racks up a sleep deficit of two hours. It might not seem like much on its own, but over the course of a standard workweek, this balloons to a sleep debt of 10 hours.
It's natural to want to snooze on your days off if you're not sleeping enough during the week. The problem is, weekend recovery sleep doesn't fully make up for sleep loss. Let's see what the research says about sleeping in and your circadian rhythms.
We tend to feel our best when we have a regular pattern of sleep and wakefulness that aligns with our 24-hour internal clocks. Known as circadian rhythms, these internal clocks take their cues from light and temperature and tell our bodies that:
Our circadian rhythms also manage metabolism, body temperature and other important functions. Interrupting these rhythms can impact physical and mental health.
When you're sleep-deprived during the week and oversleep on weekends, you're alternating between short and long sleep durations. A study by Christopher Depner and colleagues published in 2019 in the journal Current Biology concluded that this pattern of sleeping doesn't make up for sleep debt and further disrupts your natural rhythms.
In the study, a group of participants was restricted to five hours of sleep per night for a workweek and then allowed recovery sleep on the weekend. Despite attempts at catching up, the study participants carried some sleep debt over into the next work week.
The study also found participants had altered circadian rhythms on weekends because of light. They experienced increased light exposure at night from staying up later and decreased light exposure in the morning from sleeping in. Because circadian rhythms are influenced by the presence of light, this shift resulted in a delay in circadian timing. Subjects were at an increased risk of wakefulness during the night, with a significant delay in waking on the Monday morning of the second workweek.
Researchers have a name for this difference between your natural sleep schedule and the sleep you actually get: social jet lag. Like the jet lag that comes with crossing time zones, social jet lag causes sleepiness, fatigue and a decline in mood. Researchers at the University of Arizona even determined an impact on health.
So, if you shouldn't be adjusting your sleep to times that are most convenient for your work schedule and lifestyle, how can you compensate for a sleep deficit?
The best option is going to bed earlier rather than sleeping in. While you don't need to make up sleep debt to the exact hour, you may need several nights of sound sleep to compensate for the loss.
Of course, sleeping in isn't always about catching up on sleep. If you're sleeping more than usual, consult your doctor to rule out an underlying medical condition.
Consistent excessive sleep, described as more than nine hours in a 24-hour period, often occurs with a variety of neurologic, medical and psychiatric disorders. In fact, people with a mood disorder, such as depression, are three to 12 times more likely to have excessive sleep.
This brings us back to our original question — can sleeping in make you even more tired?
The bottom line is that if you're consistently short on sleep, sleeping in can extend your sleep deficit and disrupt circadian rhythms. However, if you regularly get enough sleep, the occasional day of lazing in bed should be fine as long as you're usually following a regular sleep routine.
According to Harvard Health Publishing, both too much and too little sleep affects natural body rhythms and causes fatigue. To avoid a sleep deficit, aim to get an adequate, restful sleep every night.
© 2021 American Sleep Association.