There are plenty of reasons to celebrate a heatwave, but a good night’s sleep is probably not one of them. You toss and turn, flipping the pillow over and over to try to find the cool side, coated in a sticky sheen of sweat. And the extra daylight is a mixed blessing, making it harder to drop off and trickier to stay asleep once we do. Light evenings tend to reset our body clock that’s located in our brain. Unfortunately, this is exactly the type we need to feel rested in the morning. “Our sleep cycle is governed by our sense of light and dark, or circadian rhythm,” explains Dr Guy Meadows, the co-founder and clinical director of the Sleep School app. The longer we see light, the longer our in internal clock tells our body it is daytime and needs to stay alert. When it gets dark, the body clock signals that it’s time to sleep by releasing melatonin. In summer months we secrete less melatonin, which one reason we wake up earlier and find it harder to drop off.…