From Optimising sleep for night shifts by Helen McKenna and Matt Wilkes 3rd March 2018
Night shift work happens when your body would rather be asleep. Alertness, cognitive function, psychomotor co-ordination and mood all reach their lowest point between 3am and 5am.
After a night shift is over, the worker has to try to sleep when the body would prefer to be awake. This shift away from the circadian phase compounds the fatigue and can lead to chronic sleep disturbance. There is more likelihood of occupational accidents, obesity, type 2 diabetes, heart disease and breast, prostate and colorectal cancers. Psychological and physical well being is affected and accidents or near misses when travelling home are much more likely to occur.
Performance on the night shift gets worse as people get older and it takes longer to recover from a night on.
On average most people sleep about 8 hours a night. Some people cope with sleep deprivation better than others. Performance will be impaired after two hours of sleep deprivation and gets worse as sleep debt accumulates. Therefore before starting a set of night shifts it is wise to sleep in the morning before, avoid caffeine that day, and if you can take a nap in the afternoon between 2pm and 6pm. For a nap to be most effective you need 60-90 minutes asleep.
When you start the shift, try to fit in a nap of about 30 minutes if this is the sort of job that allows this, but have a coffee immediately before the nap, and don’t have any more caffeine after the nap. Sleeping longer than 30 minutes can make you feel groggy as you move into deep sleep and are the roused from it. Caffeine can help performance but you also want to try to sleep the next morning. Avoid it for the 3-6 hours before you plan to go to sleep in the morning. If you are doing critical tasks especially between 3-5am it is wise to build in more checks to your work.
Working in bright light can perk you up on the night shift.
When it comes to eating you are probably best to eat your main meal immediately before the night shift then eat just enough to feel comfortable as the shift goes on.
Jet lag improves at the rate of one day for every hour you are out of phase. Circadian adaptation is therefore impossible during short term rotating shift work. Therefore you have to do your best to optimise your sleep between the shifts so as to keep the sleep debt minimal.
If you can possibly arrange lifts home or travelling home on public transport after a night shift, do so.
You can try to improve the situation by wearing sunglasses in daylight on the way home, avoiding electronic device screens, using blackout blinds, ear plugs and eye masks or even white noise generators. A warm bath and then sleeping in a not cold but cool room and wearing woollen nightwear may help. Melatonin taken in the morning after a night shift has been shown to improve sleep duration by up to 24 minutes. Avoid alcohol and caffeine as these won’t help. Drugs such as Zopiclone can improve sleep if taken during the day but it can be addictive and needs a prescription.
After a run of night shift work you may get into the swing of your regular routine by having a 90 or 180 minute sleep, as this is one or two sleep cycles, or sleeping in to noon and then getting up and getting outside for some exercise in bright light. Do your best to include meals at the usual times and socialise a little. You will also need to pay attention to paying back your sleep debt by going to bed earlier than usual and sleeping in later than usual for a few days. It is best to avoid day time naps during the recovery from shift phase.
The path to sleep optimisation is an individual thing. Feel free to experiment.