Because Vitamin D is involved in so much physiology there are many related factors. Low sleep and sleep debt are common and getting enough sleep is associated

Because Vitamin D is involved in so much physiology there are many related factors. Low sleep and sleep debt are common and getting enough sleep is associated with higher Vitamin D levels. Stress is common and finding ways handle stress is associated with increased Vitamin D levels. Vitamin D is present in eggs, oily fish, and organ meats. One of the most effective ways of increasing Vitamin D is to get some sun close to mid day. This is another example of cascading factors as making time to be outside at mid day tends to result in a range of other changes opening up diet options, increasing exercise, improving mood, and so on. So your knee jerk reaction is strictly speaking true yet also a distraction.