Can you "catch up" on sleep?

Lying in until 8, 9 or 10am on a Sunday - unless woken by little ones, for many of us, this is an absolute dream. Not only do we feel more rested than we have all week, it makes us feel justified if we had to skimp on sleep during the week. Surely a big lie in on the weekend reverses any loss from inadequate sleep through the week, right? Fortunately, there is some merit to this - but perhaps not as much as you think.... as you'll soon see.

Problem 1: effects of sleep deprivation begin after 1 night, not several nights. 

Lack of sleep impairs physical, mental and cognitive health - only after one night. Specifically, academic evidence indicates a 28% decline in natural killer cells, immune agents which hunt and destroy invading pathogens; and another clinical trial found cortisol, the stress hormone to make us feel anxious, can increase by 37%. A third research paper noted beta amyloid, a neurotoxin to contribute to brain fog and memory loss, can increase by 30% - again, after just 1 night of insufficient sleep.

Problem 2: even when you ‘catch up’ on sleep, you don't return to normal functioning for weeks - if at all.

If you think the weekend lie in makes up for the sleep you miss during the week; think again. A 2010 study found the consequences of ongoing lack of sleep - 4 hours per night for 5 nights - could not be restored even with even 10 hours of recovery sleep. After the lengthy rest, attention and reaction times were still below average, and fatigue was higher.

On a similar vein, another study found an entire week of recovery sleep didn't return the participants to norm - yes, an entire week. Assessing the impact of 10 nights of insufficient sleep, whereby sleep was 5 instead of 8 hours; a week of recovery sleep did not reinstate the baseline levels of accuracy and cognitive performance.

Problem 3: lack of sleep impairs metabolism (read: impairs weight loss), and recovery sleep does not reverse it.

Another reason why 'catching up on sleep' doesn't work - metabolism. One research paper highlighted if we sleep only 5 hours during the week, but 8 hours of 'recovery sleep' on weekends, even after the longer sleep time, we still show signs of metabolic impairment - reduced energy expenditure, additional calorie intake after dinner, detrimental impacts upon insulin (leading to excess sugar consumption), and increases in weight.

Problem 4: it takes longer to recover from lack of sleep than you probably think

If you lose just one hour of sleep one night, a recent clinical trial found it takes 4 days to recover - yes, 4 days. Further, it takes 9 days to recover if lack of sleep is ongoing. Here, even I am surpirsed.

So.. should we try and make up for lost sleep, or not bother? 

Despite this research, catching up on sleep - I'll still encourage it. Not so much because it restores our functioning to our best, but more so because we FEEL better. All these research papers agree - after recovery sleep, participants are less fatigued and tired, and more emotionally upbeat. Though cognitively, it doesn't improve our skills as much as we'd like, we are humans, not robots - so how we feel is just as, if not more important to consider.

So... what is the best way to catch up on lost sleep?

Though the benefits are limited, 'catching up' on sleep may still be helpful - but of course, the best remedy is prevention in the first place. Nevertheless, top tips to catch up on much needed sleep:

1. Take a daytime nap. Keep it short (less than 30 minutes), keep it dark (wear an eyemask) and keep it early (finish before 330). The only caveat to this is if you are extremely sleep deprived - e.g. less than 4 or 5 hours, try a 90 minute nap instead - but avoid waking in between. 90 minutes allows you to move through a full sleep cycle, leaving you alert upon waking. However, if you wake between 30 and 90 minutes, you'll probably wake in the middle of a deep sleep cycle, and feel extremely fatigued and groggy.
2. If you're tired enough, have an early night. We often have a lull of energy in the early part of the evening, just after eating. Hence, if this is enough to put you to bed - ride this tiredness wave and see it through to the morning.
3. Don't sleep in... unless it's only for 30 minutes. Overall, sleeping in is a problem (see below); however if it's only for 30 minutes or less, it shouldn't play major havoc on your sleep schedule. Longer than 30 minutes though - this is an issue. See, when sleeping in on a Sunday for example (e.g. until 8am), to help you stay asleep, melatonin levels will be higher than 'usual' at that time on a Sunday morning (8am). And, as melatonin operates on a 24 hour cycle, it means that 24 hours later (Monday morning, 8am), it will again, be higher than 'usual'. The problem is, with melatonin leaving us feeling tired, this is exactly how we will feel at 8am on Monday - which, given that it's probably the start of our work week, is less than ideal. Similarly, sleeping in on Sunday (say, for 2 hours) means you may not feel tired until later than normal on Sunday night (again, for 2 hours), meaning you may stay up later until you are sufficiently tired - and then end up with inadequate sleep that night, beginning the cycle of needing to 'catch up' on sleep once again.

This article is another instalment of Sleep for Success - a LinkedIn series empowering you to your best nights sleep. With sleep not only important, but imperative for optimal wellbeing and peak performance alike; it's a pleasure to leverage my 14 years of academic and professional experience to share expert tips, tricks and techniques to help you sleep longer, deeper and wake more refreshed. Supercharged by sleep, look forward to achieving more, in less time, with less effort - naturally. Please share with anyone you feel will benefit, and of course, sleep well.