I wrote this in response to someone asking about reading at bed time. I wrote it under my older username, before I had to change my email address. I’ll explain why I think this pertains to time changes and sleeping cycles:
"It would make sense that reading an iphone/computer/kindle before bed might worsen things, but not for the reason you might think. There’s a reason that our bodies work as they do, getting tired in the evening and more alert in the morning, and it’s not just because we’ve spent a day expending energy.
When light hits our eyes, it sends a signal to the brain to stop producing melatonin—the natural chemical that makes you sleepy. Naturally, as the sun goes down, and we’re exposed to less light, our brains will naturally begin the production of melatonin, preparing the body for rest, making one tired. But when we interrupt that process by adding too much bright, artificial lighting before going to sleep, we interrupt the process, setting the brain back into a more alert state, which is not what one desires before bed. This interruption disrupts sleep cycles, therefore setting up a horrible process in which you get restless, poor sleep.
Having said that: by taking away the artificial lighting, you’re allowing your body to produce melatonin, therefore preparing the brain for restful sleep. With MAV, sleep is important, so getting better sleep could explain why you’re feeling better. On a good note, if this is the cause of your improvement, reading an actual book (paper book), will not interrupt your sleep, nor impede on melatonin production. If anything, reading will relax you. But stay away from screens late at night.
Hope this helps."
Now, as for what this has to do with your question: when we go through a time change—particularly in fall, and throughout winter, when days become shorter—our Circadian rhythm (sleep cycle) gets thrown wildly out of whack, especially if nothing’s done to counteract it. As for why this happens: as I described above, sunlight has everything to do with our sleep cycles. In summer, when the sun rises before most of us wake, we wake to natural light, and the brain receives the signal through the eyes to stop producing melatonin and start producing the many chemicals that create a wakeful feeling. But when the time changes, and we rise to darkness, the brain doesn’t exactly know what to do because the eye isn’t taking in natural light. Now you have a problem, and poor sleep is at the root of it all. This disrupts the entire sleep cycle, leading to prolonged fatigue throughout the day and restless sleep at night. This, I assume, can greatly contribute to MAV. The question is, what can be done to counteract this problem?
Many people have found relief by using light therapy. You can find light therapy devices on Amazon, but they’re a little pricey, and they require that you sit in front of the light for a sustained amount of time each morning; not very feasible for everyone, and it killed my eyes. Just too bright. What I use, and what I’d recommend (and no, I don’t work for the company; I’ve just have a lot of troubles with my sleep cycle) is a wake up light. I use one made by Phillips, called the wake up light. It’s an alarm clock that simulates sunrise. Many people—particularly those living in areas where sunlight is scarce—have found them very helpful.
I hope this helps.