I find the sun my biggest immune booster and when I wake up tired, just picking up those first sun rays for 20-30 minutes on as much exposed skin as possible, while being grounded or earthed, gives me a lot of energy. Remember that we are electrical beings (so glorified batteries with 83% water and two electrical devices namely the heart and the brain) and are hardwired with the earth and wirelessly connected with the sun) since the sun provides two third of the energy levels for the mitochondria. The sun also sets our carcadian rhythm or biological clock in the morning when you do the sun rise (at 1600 Kelvin light strength) you not only tell your body what time it is, until 10am you build are the hormones from dopamine, to growth hormones, to histamine and Melatonin (sleep hormones) that the body then can release at night after 4 hours of darkness.
Everything we eat in the end is turned into electrons or pure energy so if we don't get enough sunlight, like in winter time, you guessed it,
we start to eat more to compensate with food to get enough energy. At the mitochondrial membrame (little workers in the cell that provide ATP) there are no fat, lipid or protein chain convertors, but only electron chain convertors, so yes, everything we consume turns into energy for the cells to keep going. When I then started eating raw oysters (yuk) I found more energy again, and this is because raw oysters are the highest source of DHA which builds melanopisn, which is a UV receptor in skin and eyes. A deficiency in DHA will stop you getting all the benefits from the sun.
I also found that when I use blue blockers at night to protect my eyes from blue light (all electrical light from led's pc screens, tv and mobiles is 6500 Kelvin) I sleep better. The reason is this. The sun is like a clock and our bodies are made to be up at sun rise, and in bed at dark. In the morning the sun rise has the light strength of 1600 Kelvin and it goes to 6500 Kelvin at noon and then slowly goes down again.
If you don't protect your eyes when it gets darker, you are telling your body, by watching tv, pc screen or your mobile, that it is actually noon again and your body start to make cortisol again. This is also the reason why people can't fall easily asleep anymore after they have gone to the toilet and have looked at their mobiles to see what time it was or turned the lights on.. You just told your body at 2am that it's noon again, so start making cortisol and stop releasing melatonin.
Since our bedroom is the place where our bodies should be able to repair and recove, it's very important to be protected from all light sources and to sleep as dark as possible. But, also to protect oneself from wirless radiation that falls outside our visual spectrum. While you can't see the light frequencies or radiation from WiFi, radar, towers and mobile phone with your eyes... your cells do pick it up and it affects your sleep and thus your immune system, as your body goes into a fight or flight response and that energy has to come from some where. Over time you are working towards chronic fatigue this way. Anyway, that was my two cents.