Sleep Debt: Fact or Fiction

If you’re reading this article, you’ve probably had some issues with sleeping at some stage. If not, well I’m absolutely delighted for you. There is a commonly held belief that we can incur a sleep debt. That by missing out on sleep – by chance or by choice – over time, we incur a debt that needs to be repaid with extra sleep at some stage.

I wanted to know if this was true, so I Googled.

How much sleep do we really need?

According to the Centers for Disease Control and Prevention (CDC), “Adults need 7 or more hours of sleep per night for the best health and wellbeing. Short sleep duration is defined as less than 7 hours of sleep per 24-hour period."¹

So, what happens when we’re not making the 7-hour target?

Aside from an increased risk of obesity, heart disease, diabetes, and depression - amongst other things - lack of sleep is just exhausting. It impacts daily functioning and quality of life, and consecutive nights of impaired sleep have a cumulative effect.

What about daytime napping?

Part of good sleep hygiene practice is getting up at the same time every day and going to bed at the same time every night. It also discourages daytime napping.

But when you have chronic insomnia, I’m not convinced that is always helpful. When sleep finally comes, an extra hour or two in the morning or a daytime nap feels like it offsets some of the exhaustion.

After several days of chronic sleep deprivation, it is tempting to sleep any minute that becomes available. But as frustrating as it may seem, sleeping too much can keep me stuck in the cycle.

By catching sleep at any hour, I can cause circadian rhythms – the internal clock for the sleep-wake cycle – to misalign, making it harder to re-establish good sleeping patterns. There is a difference between a daytime nap and sleeping throughout the day.

Calculating my sleep debt

So, can a sleep debt be repaid?

If I start crunching numbers, 7 hours sleep a night for 7 nights would be 49 hours. (Wow!) If I only average 4 hours a night for 4 nights (16 hours), will 11 hours in a 24-hour period for 3 nights (33 hours) have me all fresh as a daisy by Monday morning?

I don’t know, is the short answer.

What my sleep deprivation looks like

I do know this however, when I sleep poorly, I behave differently the following day. I can function with 4 hours – I’ve done it most of my life – but I feel more manic, have big peaks and troughs of energy, spend more time looking for high carb foods, my decision making is more scattered, I’m more forgetful, and I struggle not to harbour resentment towards my long-sleeping friends.

Less than 4 hours of sleep makes daily functioning very problematic. It’s increasingly difficult to concentrate on a task. I can’t find the energy required to do anything more than the bare essentials. I struggle to make intelligent decisions, be friendly and polite, practice patience or get the creative juices flowing.

One bad night versus a bad month

The science seems to be out on the reality of repaying a sleep debt – catching extra sleep on the days after those sleepless nights. Some studies have demonstrated that the average amount of sleep over the course of a month is a better indicator of cognitive performance than sleep durations immediately prior to testing.²

I guess it comes back to the knowledge that I can manage one bad night, but a bad week is difficult while a bad month leads to physical and psychological consequences.

Repaying my sleep debt where I can

In the meantime, I have come to the conclusion that short bouts of daytime napping help offset my sleep debts and that as long as I don’t nap half the day away, it is beneficial for me. Adding an hour of naps to 4 hours of sleep might not push me to that magic 7 hours for good wellbeing, but an hour is 25 percent more sleep and that can make a world of difference to my daytime functioning.

For me, repaying the sleep debt when I can, brings the rewards of increased cognition, less snacking on toast, and much calmer personal interactions with my nearest and dearest. When I can, I nap and hope that not only is my sleep debt eventually repaid, but I can bank a few sleep hours to help with the days ahead.