Unfortunate that Joshua Tree (Yucca brevifolia) are not in there. I always thought they would have a pretty fascinating root structure because of how separated they grow. Makes sense that it’s not in a Dutch database though!
You should look into CBTI, and see a sleep therapist (my insurance covered this; so I only had to pay co-pay).
In brief, the goal with CBTI is to force yourself to get out of bed at 8am (say). You can still continue going to sleep at whatever time you’re used to. So clearly, you’ll be extremely tired if you keep getting 5-6 hours of sleep. My therapist told me that I’d essentially hate him for 1.5 weeks until this keeps going. Also, no naps are allowed in this phase. At some point, your body will be so tired that you’ll just pass out at midnight.