The spring and summer months can make sleep feel impossible, with everything from sweltering temperatures and noisy late-night barbecues to rowdy birdsong and early sunrises to contend with. Numerous studies have shown that our sleep changes for the worse when spring arrives. Being stressed about it won’t help – though, of course, it is understandable to be concerned about the climate crisis that will see our temperatures reach extremes and make sleeping even harder. But on a sleepless night itself, try to relax. “It’s totally normal to have the odd bad night,” says Dr Allie Hare, sleep consultant at the Royal Brompton hospital in London. “Accept that if there is a major heatwave, you might have a couple of nights that are not quite so good, rather than getting really anxious about it and then trying to sleep. As soon as you try to sleep, you won’t sleep.” (If the sleeplessness has “gone on for more than a couple of weeks it is important that people see their GP”, she adds.) Here, experts give their advice on how to sleep better in the summer months. Consider your circadian rhythm “We all like those long evenings but exposing yourself to light late on can shift your circadian rhythm back, causing something called a delayed sleep phase, and make you want to go to sleep later than you otherwise would,” says Guy Leschziner, professor of neurology and sleep medicine at Guy’s hospital in London, and author of The Nocturnal Brain. “Obviously many people have got a normal life and they don’t want to sit behind closed curtains.” One way to balance it out is to get bright light exposure in the morning, “as soon as possible after waking”, which should, later in the day, make you feel sleepy earlier. Don’t forget bright light from screens, all year round, also has a negative effect on our sleep-wake rhythm. The right light Blackout blinds or curtains can be helpful if your bedroom gets a lot of light in the early hours of the morning. An eye mask can also help, if it doesn’t make you feel too hot and sweaty. Your room, says Hare, “doesn’t have to be completely pitch black. People can get a bit obsessed about blocking out every chink of light. It’s just about dimming the lights at sleep onset to let your melatonin levels rise [the hormone associated with sleep], and then reducing significant light intrusion in the morning. You are more likely to wake up if there’s a lot of light intrusion.” Reduce your room temperature For most of us, says Leschziner, “the best ambient temperature in the bedroom is 16-18C (61-64.5F)”. In a heatwave, he recommends draping a damp cloth over a fan, “because, essentially, the evaporation of water from the dampened cloth will cool the air that the fan is blowing over you”. Have a tepid shower or bath “We know that our core body temperature and sleep initiation are closely linked,” says Leschziner. “In preparation for sleep, our core body temperature tends to drop. Before we wake up, it rises, so there are probably some important regulatory mechanisms that link our core body temperature and sleep.” A warm or just lukewarm bath or shower about an hour before bed “causes dilation of the blood vessels in your skin so that when you get out of the bath, you can lose heat more effectively”. Others advise not to have a cold shower before bed, however tempting when the weather is hot, because it may actually increase your body temperature. “There is some scientific rationale, because a cold shower will cause your blood vessels to constrict and therefore make you less able to drop your core body temperature. So theoretically, yes,” says Leschziner, but he adds he isn’t aware of any good evidence. Keep a cool head “The brain doesn’t like getting too hot,” says Jim Horne, emeritus professor of psychophysiology at Loughborough University and author of Sleeplessness. It’s one reason your cheeks go red, particularly when you’re tired, he says, as, “your body is dumping heat”. You could open a window, but that risks letting noise and light in (if a breeze disturbs the curtains). Horne recommends a fan, which comes with the bonus of white noise – something that many people find comforting. “A fan nearby with a gentle breeze over your head is, I think, the best method. It doesn’t matter if your body gets too hot in your sleep, as long as your brain keeps cool.” Cooling tricks Leschziner has heard them all. “People try putting a pillow in the fridge or even the freezer before they go to bed. Wearing clothes that wick sweat away from your skin, because that increases the surface area from which your sweat can evaporate. And things like natural materials for bedsheets.” It’s all anecdotal, he says, but “anything you can do to try to cool yourself a little is something that is probably going to facilitate better-quality sleep”. Stick to a routine In summer, our schedules can change, from gardening into dusk, eating late or staying out with friends, and a light evening lulls us into the idea that it’s still daytime, meaning we get to bed later and later. “A regular bedtime and getting-up time is, of all the things I recommend for good stable sleep, probably the most important,” says Hare. Our habits also change – we may drink more alcohol, for instance. “Alcohol helps you fall asleep because it’s a sedative, but it disrupts your REM sleep,” says Hare. “You’re more likely to wake up in the early hours and struggle to get back to sleep.” We may be more likely to eat later too, but Hare says we should try to avoid eating a heavy meal in the two hours before bedtime “because your body can’t sleep and digest [at the same time]. Often, you’ll get problems with reflux, indigestion and bloating, and that can disturb your sleep.” A light salad is fine; a barbecued feast is not ideal. And stay off the iced coffee in the afternoon. “There’s a major genetic variability in how quickly we process caffeine, but for most people it takes a long time, so the general rule I give is to avoid caffeine after lunchtime,” says Hare. Avoid a siesta A snooze in the shade is a pleasure but Hare says she doesn’t recommend a nap, likening it to snacking between meals. “You’ll tend to struggle to get to sleep, wake up a bit early or won’t be able to maintain sleep because you’ve just reduced your appetite for it,” she says. The exception, she says, is “if you’ve had a very restricted sleep – particularly if you’ve got to drive somewhere or do something that involves important concentration – then having a nap is important because it does improve your alertness and your ability to focus. But, generally speaking, I don’t recommend naps as a routine practice. There’s evidence that they actually disturb your sleep rather than improve it.” Sleep alone (perhaps) You may find you sleep better without your partner tossing and turning with their own sleep struggles, or radiating heat. It’s “a tricky one” says Hare, pointing out that sleeping with a partner is, for many people, an important part of their relationship; it’s often the thing that the people she sees in her clinic want to get back to. “If you’re finding that sharing the bed makes you both too hot, then, yes, but I don’t generally like advising separate sleeping,” she says. “It can be hard to get back to co-sleeping if you get into the pattern of separately sleeping.” Don’t exercise too late During the summer, you may try to fit your run in during the evening when the temperature has cooled a little, but this could make it harder to sleep. Vigorous exercise will raise the body temperature, and the excitement and motivation of trying to smash your personal bests won’t help. Save it for the morning; in the evening Horne recommends “a relaxing walk, in not too bright light”. Though he also adds that – like most of this advice – this is for those vulnerable to fragmented sleep. “If you’re a good sleeper, do whatever you like.”