Napping on nightshift
Research on sleep inertia – the state you are in when you first wake up – by Centre for Sleep Research PhD candidate, Cassie Hilditch, has particular relevance for nightshift workers in safety critical industries such as health care or transport, who have to return from breaks and operate at full capacity.
Post nap alertness is critical for workplace safety, particularly for those in industries such as health.
“Sleep inertia is the groggy feeling most people experience when waking up, and is characterised by slow reaction times, poor decision-making and reduced information processing,” Ms Hilditch says.
“This doesn’t matter for people getting dressed in the morning, but for workers in industries such as health, post nap alertness is critical for workplace safety,” she adds.
Ms Hilditch's study finds a 30 minute nap during a night shift produced long lasting sleep inertia, with recovery times of up to 45 minutes.
A 10 minute nap during a nightshift, however, can help stabilise performance during the hour after waking, with little to no sleep inertia.
Her research shows the importance of workers allowing time between a nap and the recommencement of work.
“Our research suggests that if you have a 30 minute break in a shift at night, it’s better to take a 10 minute nap at the start of your break. Don’t take a 30 minute nap if you need to return to work straight away,” she says.
“Our participants were well rested before the study, so these are likely to be best case figures, as shift workers may already have cumulative fatigue which could prolong recovery from sleep inertia. In the real world, people are carrying a lot of sleep debt.”
Cognitive tests also reveal participants tend to overestimate their abilities after a nap, with the gap between perception and reality producing further risk.
“If sleep inertia persists beyond your break, and you think you’re more alert than you actually are, then there is a clear safety risk,” she says.
“One of the challenges is getting people to recognise their limitations. Shift workers might think that since they’ve been doing shift work for six years they are fine, but they might not be – many studies support this.
“Trying to give people advice on how to schedule shifts made me realise we don’t know enough to provide all the details.”
While her research is offering some answers, it has also given her some first hand experience in sleep deprivation.
“The irony of sleep research is the long night shifts you have to do to be able to study it,” she says.
Ms Hilditch recently presented her research at the Australasian Sleep Association Annual Scientific Meeting in Perth, where she won the New Investigator Award, and has also presented a poster at a European Sleep Research Society conference in Tallinn, Estonia.
Three tips for napping on nightshift
- Always include a buffer zone between a nap and starting work.
- Remember that people who are sleep deprived judge their own performance badly – you might think you’re doing better than you actually are.
- Naps are still important and beneficial – you just have to let the sleep inertia wear off afterwards.
