It is a truth universally acknowledged that a new parent who has been up half the night with a crying baby must be in want of a coffee.
But while coffee has long been the crutch of the sleep deprived, a new (and slightly alarming) study has found that caffeine has little to no effect after just three nights of restricted sleep.
The researchers conducted a double blind, placebo-controlled study. Sleep was restricted to five hours of time in bed for a total of five days, and participants were either given 200mg of caffeine or a placebo twice daily.
To determine the effect of the caffeine, the participants completed an hourly cognitive task. Mood and wakefulness tests were carried out six times a day.
And what did the results show? Caffeine significantly improved cognitive performance during the first two days – but not for the following three days of sleep restriction.
Research scientist and lead author Dr Tracy Jill Doty said the team was surprised by the results of the study.
"These results are important, because caffeine is a stimulant widely used to counteract performance decline following periods of restricted sleep," she said.
"The data from this study suggests that the same effective daily dose of caffeine is not sufficient to prevent performance decline over multiple days of restricted sleep."
While the results were "surprising" for the scientists involved in the study, they can seem catastrophic for new parents who face months (and in some cases, years) of sleep deprivation.
Lana Hall, a psychologist and author of the book, How to Stop Worrying and Start Sleeping, notes that sleep deprivation should not be underestimated.
"Lack of sleep takes who you are and brings you down a few notches in every way: you're less energetic, more emotional, have less willpower, are more indecisive, less clear headed, and more likely to think negatively. We really need our sleep," she says.
If we can no longer rely on coffee the morning after a baby-induced all-nighter, then what can we rely on?
Experts suggest that snacking on energy-rich foods such as nuts or fruit, or even wholegrain toast and baked beans, will make you feel more energised. We might crave high-sugar, high-fat comfort foods, but they're likely to leave us feeling even more lethargic.
Hall also suggests that tired parents try to develop some 'coping statements' – short phrases you can use tell yourself that will help you to feel more calm and relaxed.
"Try some statements which acknowledge how you're feeling, but are still hopeful too – 'I'm so tired now, but this stage won't last forever', 'This is really difficult, but I can survive this', 'As long as I meet my baby's needs, I'm doing a great job.'
"Some people also find remembering that they're not the only mum doing this right now, or focussing on what they're grateful for – a healthy baby, even if they do cry a lot! – is helpful too," she says.
But when it comes to the realities of sleep deprivation, mums are the biggest experts of all.
Jo, who has a three-month-old, says that the best solution to lack of sleep is to try and get some sleep. "I try to sleep when the baby sleeps, even if it's just half an hour. It makes a huge difference," she says.
Similarly, Kim-Marie found early nights were the key to staying sane on lack of sleep: "I used to put my son down at 7pm and go to sleep at 8.30pm, wake up to feed him once or twice, then sleep until he woke up in the morning," she recalls.
Another common coping strategy is simple fresh air. Kerry, the mum of a two-year-old says: "Everything seems better outside."
Likewise, Jess says: "Getting out in fresh air really helped. I found it much harder to stay and home and dwell on it."
So while caffeine might not work the way you'd like, walking to your nearest coffee shop will still do you good.