Sleep Hygiene, Night Starvation

I had never heard the phrase 'sleep hygiene' before last night, when I heard it twice - once on the radio and once on TV - within ten minutes. It's got nothing to do with cleanliness but is about arranging matters so as to get a good night's sleep - saying no to that third espresso, drawing the curtains, turning off the light and the TV, that kind of thing. It reminded me of a phrase from the now distant past that I had all but forgotten - 'night starvation'. This non-existent condition was dreamt up in the 1930s to market Horlicks, a sweet malty milk drink that is still available in various forms today. The notion of 'night starvation' caught on, and was still going strong in my childhood. I remember ads in the women's magazines that made up rather too much of my boyhood reading in which a worried housewife, who, despite sleeping well, was feeling tired all the time, consulted her doctor about it. This reassuring figure, in a pinstripe suit, would remove his glasses and suggest that 'You may be suffering from night starvation'. To remedy this, he would recommend - you guessed? - Horlicks. They don't make them like that any more (they're not allowed to) - but why did the notion of 'night starvation' take such a hold? I fancy it was because it sounded faintly alarming (and yet easily remedied), and because in those days of non-stop eating, it seemed barely credible that the human frame could survive the hours between the late supper and the cooked breakfast without further nourishment.