Winter Depression is a common observed phenomena, especially in Colder countries in North.
Seasonal affective disorder (SAD) is depression that gets triggered by a change in seasons, usually when fall starts. This seasonal depression gets worse in the winter before ending in the spring
People with seasonal affective disorder may also have other mental conditions, such as:
Anxiety disorder.
Attention deficit hyperactivity disorder (ADHD).
Eating disorder.
Panic disorder.
(https://my.clevelandclinic.org/health/diseases/9293-seasonal-depression)
So people who have seasonal affective disorder may have signs of depression, including:
Sadness.
Anxiety.
Carbohydrate cravings and weight gain.
Extreme fatigue and lack of energy.
Feelings of hopelessness or worthlessness.
Inability to concentrate.
Irritability.
Limbs feeling heavy.
Loss of interest in usual activities, including withdrawing from social activities.
Sleeping more.
Cause :Vitamin D deficiency due to less sin exposure.
Treatment : Sunlight and Vitamin D supplement.
Many researches have also linked Vitamin D deficiency with Panic, anxiety etc.
(https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5922262/&ved=2ahUKEwjfkNOej9_wAhWRzzgGHSMwAckQFjAKegQIEBAC&usg=AOvVaw34y_pysL2OjHNA2xheljTA)
The Covid lockdown has also brought months of house restriction and minimal sun exposure.
In such a scenario depression, panic, anxiety etc are very likely, esp with continuous bombardment of bad news and negativity.
In such a scenario proper Vitamin D supplement may be advisable, especially if such symptoms occur.