A lot of people can't get used to the short days or longer nights during the winter months. There are a lot of theories as to why that occurs. One of the theories is that we become de-synchronised with the light-dark patterns because we don't get enough light during the day. So, some people can't really adapt to that. So they start having feelings like depression, withdrawal, carbohydrate craving, weight gain. And that typically goes away during the summer months. So that's really what characterises what we call Seasonal Affective Disorder known as 'winter blues'. I think there are huge individual differences, but we know of studies where it appears that that maybe 20 minutes of daily dosage of strong light is enough. And then we're talking about a light that resemble a daylight or an outdoor exposure. And this light dosage should be presented during morning hours. There's a couple of things that can be done. First of all, obviously go outdoor during the day. If you can, spend one to two hours outside. If you can't do that, sit by a window. But don't sit against the window. Sit facing the window because that's where you want to get the light. You want the light at the eye. And the third option is (to) increase the amount of light that you have.