Several more conservative and safe interventions should be attempted to help with insomnia related to sleep apnea before considering any cannabis product. First, you should have a sleep study to determine if you have central or obstructive sleep apnea. If you test positive for either you should review your list of medications with your sleep doctor or primary care doctor to make sure none of them are aggravating your apnea. Assuming you have obstructive sleep apnea which is far more common, you should consider a positive airway pressure machine (CPAP). This machine helps keep your airway open at night so you can breathe more easily and get good quality sleep. You should also work with your doctor to treat underlying issues such as obesity or any other airway disease which are often associated with sleep apnea.
If you've successfully implemented these interventions and already have good sleep hygiene but still have insomnia then you may consider a cannabis product to help with sleep. A low THC Indica derived product, specifically a high CBD low THC oral tincture is probably your best bet. Some cannabis products marketed for sleep contain high THC concentration/doses. Although these products may get you to sleep faster they will likely lead to poor quality sleep since high THC has been shown to cause poor REM sleep. Remember to "start low and go slow" when using any cannabis product and carefully monitor if your sleep and daytime fatigue symptoms are getting better or worse.