A few things you could try: taking a magnesium supplement, use a weighted blanket, add some exercise to your routine. Is there noise that might be waking you up? A white noise machine or earplugs could help. Are you sharing your bed with someone? Their tossing and turning could affect your sleep, so fixing your bed frame and getting a mattress which isolates motion could both help. Is your life stressful? That could be something else to address.

Finally, keep in mind that possibly, these wrist sensors may not actually be able to detect deep sleep all that well.