Hi.
Your mother is probably suffering from some type of sleep disorder, most likely insomnia. There can be several underlying causes such as stress, depression, anxiety, medications, medical disorders, poor sleep hygiene and declining hormone levels (in menopausal women) for a disturbed sleep.
You should ask your mother to follow proper sleep hygiene like avoid going to bed unless she is sleepy , have a warm bath each night before bed, stop worrying , avoid caffeine, alcohol and tobacco, avoid reading or watching TV just before going to bed , follow a regular schedule. Her bedroom should be a quiet, dark, and cool.
If she sees no improvement, she should consult a sleep specialist with a sleep diary which will help the doctor see her sleeping patterns.
The doctor may advise a polysomnogram (an overnight sleep study) or prescribe some medication to treat insomnia (hypnotics). He or she may also advise some Cognitive behavioral therapy (CBT) which might improve her sleep. The different approaches used are stimulus control, sleep restriction, relaxation therapy, psychotherapy and maintaining sleep hygiene.
Sleep therapy along with sleep hygiene in due course of time helps the patient get proper night sleep.
Take care!
If her normal test reports do not include being evaluated by a sleep doctor and having a sleep study, that may be the next step.