Sleep banking has its roots in the military, where it was first investigated in 2009 as a possible strategy to reduce fatigue in soldiers before missions that made it difficult to sleep.

Small studies support the idea that banking sleep can improve performance and alertness during subsequent sleep restriction.

“I usually recommend that people go to bed an hour earlier and give themselves another hour to sleep in, so like a little bit on either end,” said Tracy Rupp, the scientific director of the Henry M. Jackson Foundation for the Advancement of Military Medicine. “Whatever you can do to bolster those reserves and give yourself extra levels of restorative resources should have some benefit.”

Experts also suggest trying the strategy before any event that takes a physical toll, such as surgery, childbirth, or a marathon.

However, similar to catching up on lost slumber, sleep banking is not meant to replace consistent, quality rest.

“If you maximise your total amount of sleep leading into a short-term scenario where you know you’re not going to get enough sleep, sleep banking can help mitigate the negative effects,” said Christopher Depner, an assistant professor of health & kinesiology at the University of Utah. “But if you do it repetitively all the time, that type of a pattern can be really detrimental because you still suffer the consequences of not getting enough sleep.”

Benefits of sleep banking

In 2009, Rupp and her colleagues at the Walter Reed Army Institute of Research tested the effects of extending sleep on 24 civilian and active duty military personnel aged 18 to 39. They were randomly assigned to either a sleep extension group who spent 10 hours in bed, or a control group who slept the usual amount per night for one week.

Afterward, participants went through a sleep restriction phase, where they could spend only three hours in bed for seven nights. Finally, they had a recovery period of eight hours in bed for five nights.

The researchers then administered tests to measure participants’ alertness and performance. For alertness, the participants lay on a bed in a dark room, trying to stay awake for as long as possible. Falling asleep more quickly meant that a person was more objectively sleepy and thus less alert.

For performance, their reaction time was recorded by having them press a button as soon as a visual stimulus appeared on a screen. A shorter reaction time translated to a better performance on the test.

The results demonstrated that banking sleep not only improved both alertness and performance during subsequent sleep loss, but also facilitated a faster recovery.

During the sleep restriction phase, the extended sleep group – those who spent 10 hours in bed before the sleep restriction – outperformed the control group on both tests.

And during recovery, the extended sleep group had a much shorter average reaction time after only one night of good rest, and maintained a stable level of improved performance, whereas the control group needed all five nights to gradually improve.

“The extended group just did better. Their reaction time was faster, they weren’t as objectively sleepy, and they also recovered more quickly,” Rupp said. “We argue that sleep banking is not simply paying back sleep debt, but it’s actually building up this reservoir of sorts that can be used later when needed.”

A 2015 study of 14 healthy men reported similar findings, that six nights of extended sleep could improve alertness and reduce sleep pressure throughout a subsequent 21 hours of total sleep deprivation.

And a 2019 systematic review showed that banking sleep has a positive effect on performance, acute fatigue and the ability to stay awake. Participants in the five studies mentioned in the review included shift workers, electricians and medical residents.

“Physicians can go 24 hours without sleep because they’re on call or held over, and a study found that banking sleep had a favourable impact on patient safety,” said P. Daniel Patterson, associate professor of emergency medicine at the University of Pittsburgh, who wrote the review. “The main takeaway from this is, sleep banking is a good thing.”

‘Sleep is medicine’

Sleep banking can lead to less fatigue and better performance for shift workers – people on night shifts, long-duration shifts, or rotating shifts, Patterson said.

They consistently get less sleep than non-shift workers, and there are more cases of insomnia among people with this type of schedule than the general population. Shift work has also been associated with a higher risk of cardiovascular disease, obesity, type 2 diabetes, several types of cancer and other health consequences.

“Sleep really is medicine,” said Patterson, who analyses how shift work affects the health and safety of emergency medical services professionals. “There are so many positive things that happen when we sleep, physiologically, and from that perspective, the longer you can give your body to recover and rest, the better – especially for shift workers.”

Patterson advises that “If you have the flexibility and the opportunity, trying it one or two days prior to your scheduled shifts can lead to some benefits.”

Sleep banking for physically taxing events

Other research points to the benefits of sleep banking in preparation for other physically taxing events such as an operation or an athletic event.

A 2017 study found that participants who spent two extra hours in bed per night for one week before knee or hip replacement surgery reported less pain and made fewer requests for morphine than a control group.

And a 2019 study showed that endurance cyclists or triathletes who extended their sleep for three nights performed better on time trials compared with those who got a normal amount of sleep.

Tips for banking sleep

For many people, fitting in more hours of sleep into an already packed schedule isn’t easy. But for those who want to try sleep banking, these strategies might help.