Sleep a lot? You might have a heightened risk of stroke, study says

I can't see a cause and effect here at all. But post-stroke I don't think I really have ever slept more than 8 hours straight although I would sleep during the day whenever possible.
What a waste of time, so instead of actually solving some of the problems in stroke they went for this fairly useless research that doesn't help survivors at all.
The article here:
Sleep a lot? You might have a heightened risk of stroke, study says
Older adults who said they slept more than eight hours were 46% more likely to suffer strokes in the next decade than adults who slept for six to eight hours, according to an analysis published Wednesday in the journal Neurology. Even worse, the stroke risk for people who went from sleeping less than six hours to sleeping more than eight hours was nearly four times greater than for people who consistently got six to eight hours of ZZZZs.
 ------------------------------------------------------------------------------------------------------------
The abstract this is based upon here:
Sleep duration and risk of fatal and nonfatal stroke A prospective study and meta-analysis

1. Yue Leng, MPhil,
2. Francesco P. Cappuccio, MD,
3. Nick W.J. Wainwright, PhD,
4. Paul G. Surtees, PhD,
5. Robert Luben, MSc,
6. Carol Brayne, MD and
7. Kay-Tee Khaw, MD

+Show Affiliations

| + Show Full Disclosures

1. Correspondence to Dr. Leng: yl411@medschl.cam.ac.uk

1. Published online before print February 25, 2015, doi: 10.1212/WNL.0000000000001371 Neurology 10.1212/WNL.0000000000001371

• Free via Open Access: OA
• Abstract
• Full Text (PDF)

1. Also available:
2. Data Supplement
3. Accompanying Editorial

Abstract

Objective: To study the association between sleep duration and stroke incidence in a British population and to synthesize our findings with published results through a meta-analysis.

Methods: The prospective study included 9,692 stroke-free participants aged 42–81 years from the European Prospective Investigation into Cancer–Norfolk cohort. Participants reported sleep duration in 1998–2000 and 2002–2004, and all stroke cases were recorded until March 31, 2009. For the meta-analysis, we searched Ovid Medline, EMBASE, and the Cochrane Library for prospective studies published until May 2014, and pooled effect estimates using a weighted random-effect model.

Results: After 9.5 years of follow-up, 346 cases of stroke occurred. Long sleep was significantly associated with an increased risk of stroke (hazard ratio [HR] = 1.46 [95% confidence interval (CI) 1.08, 1.98]) after adjustment for all covariates. The association remained robust among those without preexisting diseases and those who reported sleeping well. The association for short sleep was smaller (and not statistically significant) (HR = 1.18 [95% CI 0.91, 1.53]). There was a higher stroke risk among those who reported persistently long sleep or a substantial increase in sleep duration over time, compared to those reporting persistently average sleep. These were compatible with the pooled HRs from an updated meta-analysis, which were 1.15 (1.07, 1.24) and 1.45 (1.30, 1.62) for short and long sleep duration, respectively.

Conclusions: This prospective study and meta-analysis identified prolonged sleep as a potentially useful marker of increased future stroke risk in an apparently healthy aging population.