Feeling a bit groggy lately? Suffering from tiredness, even though you went to bed at a decent hour last night?
Yes? Then let me ask you this (without getting too personal): Have you been perusing your tablet PC or your smartphone just before turning in, maybe even while under the covers?
Well, silly you. You might as well blast the Foo Fighters or the University of Southern California marching band through loudspeakers to help take you off to slumber. Or something like that.
That's because the screen on your omnipresent mobile device emits light in the blue spectrum, which suppresses melatonin, a hormone that your brain normally secretes at bedtime and that is essential for sleep. The absence of melatonin disrupts the body's natural circadian rhythm, University of Hertfordshire psychologist Richard Wiseman explained on BBC TV.
Bedtime screens are a double whammy because people use them for activities such as social media, which are stimulating and thus subvert sleep, he added.
"I think we're facing a real problem here," said Wiseman, who recommended at least turning down the brightness if you must look at your screen at bedtime.
While neurologists have known for years that screens - including televisions - mess with melatonin, the emergence of mobile devices like tablets, smartphones and laptops has created more of a problem because people readily take them to bed and are also much closer to the light source than when watching, The Telegraph noted.
So tonight, as you snuggle up with your gorgeous iPad Air, recite this: