There’s no one way to answer this question as it lies somewhere in the gray area of individual personality. Here’s the good, bad and ugly.

Good

Lying in bed can be a refuge for the high performer and high achiever. The luxury of sleeping in was likely nothing short of a distant dream for this personality type before Covid 19. Any activity done, including working from your bed, in moderation can be good for your mental health. 

Bad

You mentioned this in your inquiry. Low activity can indeed lead to bouts of extreme sadness. Depression comes into play when these bouts of sadness last for an extended amount of time and leave an individual feeling hopeless and unmotivated to do anything. Whenever a person’s daily activity is affected significantly, then we are possibly facing a diagnosis. One might note, however, that this particular diagnosis is on a spectrum ranging from mild to severe. 

Ugly

Needless to say, lack of activity can lead to other challenges such as weight gain, deficiency, and lack of motivation, low self esteem, etc. If you are one who lives alone during this time of quarantine, I would suggest some sort of spontaneous activity throughout the day. If you choose to sleep in, be intentional about getting up to walk your dog. If you choose to spend the day in bed on your computer, choose to put on some music while cooking dinner and dance. Movement increases endorphins in your brain as well as other major health benefits. In short, listen to your body. If you enjoy sleeping in, then do so. If you are beginning to feel yucky and your mood is a little off from being in the bed, adjust your schedule a bit. There’s no right or wrong to this. We are all simply adjusting to our new normal.