How much sleep have you managed to get over the holidays? Most teachers spend the first week jolting awake at the time their alarm usually goes off, panicking that they will be late for work. Gradually (children permitting), they adjust. Lie-ins, late nights socialising and quiet days relaxing become the norm. Routine goes out the window and the weeks start blurring together.

It may sound like an ideal remedy after a sleep-deprived term time. But, actually, it might not be. Sleep patterns don’t like change and extensive disruption - regular lie-ins, for example - can cause serious issues come September, experts warn.

Dr Guy Meadows, clinical director of the Sleep School consultancy, explains problems arise because we naturally seek out routine. “The human body loves regularity, specifically our internal body clock,” he says. “There are 20,000 clock cells in the suprachiasmatic nucleus in your brain, and this is responsible for keeping every biological process on time.”

It’s surprisingly easy to throw off the calibration, so these clocks don’t work as well. “A typical scenario might be that a teacher is naturally an evening person,” Meadows says. “School holidays start and they slip into a routine where they stay up late until 2am and then get up between 10am and midday. Then they do it for the next six weeks and their body clock becomes trained to it.

“The night before having to go back, they say, ‘Oh no - I’ve got to get an early night’ and head to bed at 10pm. But their body clock is saying, ‘I’m sorry, that isn’t happening. We’ve got six weeks of hard data to say we release the sleep hormone at 2am, not 10pm.’ ”

‘Social jetlag’

This phenomenon can have an impact on those first few weeks in school, an effect that has been termed “social jetlag”.

“When you return to work in September after having six weeks of disrupted sleep pattern, then this will have a similar effect on your body as being jetlagged - we call this social jetlag,” explains sleep expert Dr Neil Stanley, author of How to Sleep Well and former chair of the British Sleep Society. “You’ll feel out of sorts and not at your best, which is not ideal for the first day of school. For some people, it can take a couple of weeks until you return to normal.”

Meadows says it can become a vicious circle: “In September, these teachers who have disrupted their sleep patterns will start to worry and panic, and in desperation start trying sleep aids like podcasts or the television. Then the next day, they start worrying about not sleeping, which puts tension on to the next night, and then it snowballs. They will then try to implement a big routine - and it puts sleep up on a pedestal. But sleep is a biological process you can’t control, and the harder you try to get it, the further away it goes.”

You may argue the effect should be no worse for teachers than anyone else returning to work after a holiday. But Meadows explains that the length of teachers’ summer break makes sleep dysregulation worse, citing the effect of daylight saving time as an example.

“More than a billion people are affected when we lose an hour after the clocks change. The morning after, we see a 24 per cent increase in heart attacks,” he says (Sandhu et al, 2014, Open Heart, bit.ly/SleepHeartBMJ).

Researchers have also identified an increase in traffic accidents, he adds: “And that is just with an hour’s loss. In the holidays, teachers can shift their sleep pattern by two or three hours.”

If you suspect this article may be about to suggest that you reassess your summer slumber, you would be … right. Stanley says preservation of sleep routines is better in the long run. “The tendency to drift over the summer from your routine might seem like a positive thing: you’re relaxing, you’re no longer a slave to the alarm clock, you’re catching up on your sleep,” he says. “But it is actually better to try to preserve your routine.”

The natural response is to ask how, then, are you meant to catch up on sleep? But your lie-ins were never actually allowing you to do that, Stanley argues.

“You can’t live badly the rest of the year and expect to be able to catch up over the summer,” he explains. “If you sleep more during the whole summer break then, actually, you might be chronically sleep-deprived, and what you need to do is change your lifestyle and get the sleep you need every night, not just during the summer.”

If you are desperately in need of sleep, then you should change your normal habits urgently. Chronic sleep deprivation happens when sleep has been curtailed for a significant amount of time. Your body is never able to catch up because it is so far in deficit.

Stanley warns teachers to look out for symptoms if they know they’re regularly not getting quality sleep. “There are obvious signs of chronic sleep deprivation: feeling more tired, napping during the day, feeling like you have a mental fog. If you’re tired at 10am, then that is a big sign that you’re chronically sleep deprived because this should be your peak.”

But if chronic sleep deprivation is not a factor, and you just want to maximise your rest in the holidays, how should you approach snoozing during the six-week break?

Wake-up call

Meadows says the key to successful sleep is to slowly trick your body back to a normal pattern. “You deal with the adjustment much in the same way as you prepare to overcome jetlag,” he says. “So where you’ve gone to bed two hours later, pull it back by 15 minutes every couple of nights, and your body clock won’t have too much of a disturbing effect.”

However, Stanley advises that, rather than allowing their body clocks to shift in the first place, teachers should try to keep to their normal routine. “The single most effective thing you can do for your sleep is to maintain a fixed wake-up time, seven days a week, 365 days a year. If you have a fixed wake-up time, your body and brain start waking up around 90 minutes before you wake up, but if you don’t have that time, your body can’t prepare.”

Instead of teachers satisfying their sleep cravings with late alarms, Stanley urges them to give afternoon napping a try: “If you’re tired, then the most effective way to get more sleep is to have a nap. It’s much better than having a lie-in.”

So, how can you ensure these naps are time well spent, or that they happen at all?

1. Make it 20 minutes or two hours

“A 20-minute power nap is good for boosting performance, but a siesta-style two-hour nap gives you the benefit of sleep,” Stanley advises. Beware the temptation to hit snooze during your nap, though, or you’ll make things worse for yourself.

“You must set an alarm on your phone for [no earlier than] two hours because you don’t want to wake up in your deep sleep, as then you’ll feel like you’ve been run over by a bus,” he warns. “Also, if you sleep for too long, you’ll over-nap and won’t be able to sleep later that night. And don’t use the snooze button!”

2. Block out the world

Just like when a toddler naps, it is a sensible idea to take yourself away from distractions. “A good nap requires you to withdraw from the environment, so you need to be able to disengage from where you are,” Stanley says.

3. Consider comfort

If you feel yourself drifting off on a sunlounger or your sofa, the worst thing you can do is stay put. “Don’t lie down on the couch, it isn’t comfortable - you’ll wake up with a painful neck,” Stanley warns. Instead, he suggests that “you should get into bed with earplugs and eye shades”.

4. The duller, the better

If you’re somewhere with background noise, it might help to try to block it out. “Listening to something that isn’t stimulating or interesting is a good way to drift off,” Stanley recommends.

5. Time it right

If you pay attention to your internal body clock, you’ll probably find that after you’ve eaten your midday meal, your body will be craving a nap.

“The best time to have a nap is in the afternoon when you have a natural dip in performance,” Stanley advises. This means you can have a nice afternoon and evening, and make the most of the longer hours of sunshine.”

6. Exercise first thing

Meadows recommends that, first thing in the morning, you should make it clear to your body the day has begun. “When you get up, open the curtains, have a shower, eat and move, you give your body all the signs that it is morning,” he says.

Stanley agrees and adds exercise to that list: “The best time to exercise is in the morning when you get a lovely bathing of blue light from the sun - you’re telling the body it is daytime. You need to do something during the day to earn your sleep.”

Grainne Hallahan is a senior content writer at Tes

This article originally appeared in the 30 August 2019 issue under the headline “Enjoyed your summer lie-ins? Prepare for a body clock shock”