Why do I wake up feeling sad sometimes?

During sleep we process our day, feelings and memories. If something sad comes up, we might wake up just as we wake up when we dream something scary because our brain works a lot on these things and maybe translates them into dreams who travel into our subconscious mind and affect us even if we sleep. We wake up sad but often can't remember what we dreamt.

Everyone has a different reason for being sad, sadness comes in many forms. So I don’t know why you wake up feeling sad, but I think it’d be a dramatic difference if you made a conscious effect to remember that you’re in control of your emotions. Planning a fun activity to look forward to when you wake up is a great way to beat that sadness. Wake up and journal, make tea or coffee, etc.

Because something causes you to be sad. An event, brainjuice or whatever. It does implicate that you haven a sad attitude to begin with.

It could be due to a chemical unbalance in the brain, or even due to having a bad dream and your body isnt fully awake

Well, that's obvious! Because I woke up, duh! Maybe I didn't get enough sleep. Maybe I didn't have a good day before hand. I guess there are many factors.

There could be any number of reasons, but a big cause of morning sadness is often broken sleep; you can avoid this by practising good sleep hygiene. Establish a bedtime routine, try to avoid caffeine after 6PM, and try not to use any devices or watch TV in the hour before bed. If you wake and find yourself unable to settle, get up and do something mundane - folding laundry is a good one! - for about 10 minutes, then return to bed and try to sleep again.

Maybe tou had a bad dream? Don't let it keep you down. Just keep your head up and start off positively.

Consider experimenting with gratitude journal - 5 things your thankful for before you sleep and possibly upon awakening. We feel the way we think. What suboptimal thoughts might be promoting inappropriate sadness?